F1000ResearchF1000Research2046-1402F1000 Research LimitedLondon, UK10.12688/f1000research.162331.2Research ArticleArticlesAccuracy of Systemic Inflammatory Indices in identifying Neonatal Sepsis in preterms in a tertiary care hospital in Mangalore
[version 2; peer review: 4 approved with reservations, 1 not approved]
GMSmrithiConceptualizationData CurationFormal AnalysisInvestigationMethodologyProject AdministrationResourcesSoftwareVisualizationWriting – Original Draft PreparationWriting – Review & Editinghttps://orcid.org/0009-0001-4653-38011RenganathanGayathriConceptualizationFormal AnalysisMethodologyProject AdministrationSupervisionVisualizationWriting – Original Draft PreparationWriting – Review & Editinghttps://orcid.org/0009-0009-0116-6858a2D'saSmithaData CurationFormal AnalysisSupervisionVisualizationWriting – Review & Editing2
Kasturba Medical College Mangalore, Manipal Academy of Higher Education, Manipal, India
Department of Pediatrics, Kasturba Medical College Mangalore, Manipal Academy of Higher Education, Manipal, Indiagayathri.renganathan@manipal.edu
The utility of Systemic Inflammatory Markers (SIMs) as accurate indicators of neonatal sepsis in the Indian population has not been shown in any current research. This study will assist in determining whether SIMs can be used to predict neonatal sepsis at the bedside and as an early sensitive predictor of sepsis in preterms.
Methods
A case-control study was done, where the Systemic Inflammatory Indices of the two groups of preterms – one control group without sepsis and one case group with sepsis–were compared to assess their value in predicting Neonatal Sepsis. Data from 138 preterm neonates were used in the present study. Systemic Inflammatory Indices were calculated from the collected data using the following formulae:
1) Systemic Immune Inflammatory Index (SII)=[platelet/lymphocyte]∗Neutrophil
2) Systemic Inflammation Response Index (SIRI)=[monocyte/lymphocyte]∗Neutrophil
3) PanImmune Inflammation Value (PIV)=Platelet∗[monocyte/lymphocyte]∗Neutrophil
4) Neutrophil to Lymphocyte Ratio (NLR)
5) Platelet to Lymphocyte Ratio (PLR)
6) Monocyte to Lymphocyte Ratio (MLR). These values from both the case and control groups were compared.
Results
Platelet count had the highest predictive value, with an AUC value of 0.715 and optimal cut-off value of 219500. It had a sensitivity of 75.4 and specificity of 65.2. PIV had an AUC of 0.665, a sensitivity of 60.9, and a specificity of 68.1. For PLR, Sensitivity and specificity were 72.5 and 58, respectively, with an AUC of 0.668. With sensitivity and specificity of 66.7 and 62.3 respectively, SII had an AUC of 0.65.
Conclusion
There was substantial correlation between the studied hematological indices and positive cultures, suggesting their potential role as inflammatory markers. Larger prospective trials should be conducted to further validate their potential clinical value.
Neonatal SepsisPreventionPretermInflammatory markersEarly diagnosisThe author(s) declared that no grants were involved in supporting this work.Amendments from Version 1
Thank you for your constructive feedback. We have revised the manuscript accordingly. The abstract has been modified as suggested, and the manuscript has been aligned with the STROBE checklist. The summary of evidence has been refined for clarity and conciseness. The methodology section has been strengthened with clarification of the sample size calculation, culture methods, matching process, and inclusion of a study flow diagram. The results have been rewritten to avoid overinterpretation, emphasizing associations rather than predictions, and the discussion has been revised accordingly. The results tables have also been updated to improve clarity.
Introduction
Dysregulation of the host response to any systemic bacterial, viral, or fungal infection within day 28 of the life of both term and preterm newborns can result in neonatal sepsis, a potentially fatal and life-threatening illness.
1 It is categorized based on onset - early-onset sepsis (EOS), diagnosed at or before 72 hours of life (some define as 7 days), and late-onset sepsis (LOS), diagnosed after 72 hours.
2
Neonatal sepsis accounts for approximately 8% of all neonatal fatalities. Particularly in low- and middle-income nations, it is the primary cause of neonatal morbidity and mortality.
3 The approximate statistic for EOS is 2,496 in 100,000 live births, that is 2.6 times greater than the incidence of LOS, which is 946 per 100 live births, per a systematic review & meta-analysis.
4 The highest rate of clinical sepsis (17,000per 1,000,000 live births) has been reported in India.
5 The fatality rate due to sepsis in Indian newborns ranges from 25% to 65%.
6
Blood culture remains the gold standard for diagnosis,
7 but results take 48–72 hours, and lack of distinct early clinical signs make timely diagnosis difficult.
8,
9 Therefore, a sensitive and simple bedside diagnostic tool is required for early detection of newborn sepsis.
According to studies, newborn sepsis can be accurately predicted by the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and Systemic Immune Inflammatory Index (SII).
10 Other indices like Monocyte-to-Lymphocyte Ratio (MLR), Systemic Inflammation Response Index (SIRI), and Pan Immune Inflammation Value (PIV) have been demonstrated to be higher in EOS.
11 We aimed to determine whether the SII, SIRI,MLR, NLR, PIV, and PLR are valuable markers for the early diagnosis of neonatal sepsis in preterms in the Indian population.
Summary of evidence
According to Zhu et al., PLR, SII, and NLR are all accurate indicators of newborn sepsis, with SII having the best predictive value.
10 SIRI was found by Cakir et al. to be a good indicator for identifying early-onset sepsis in very low birth weight preterm infants, especially when paired with additional markers.
11 The prognostic significance of NLR and SII for newborn sepsis in babies with congenital heart disease was shown by Aydogan et al.
12 Güngör et al. found SII to be a predictor of urinary tract infections in neonates,
13 while Runqiang Liang et al. highlighted its role in diagnosing serious bacterial infections.
14 In premature infants, elevated SII levels were also linked to respiratory distress syndrome.
15 Increased SII, SIRI, PIV, and NLR values were observed in infants with hypoxic–ischemic encephalopathy.
16 Higher SIRI and SII levels were linked to a higher risk of secondary infections in preterm newborns, according to Chen et al.
17
The utility of SII, NLR, SIRI and PLR in predicting outcomes in inflammatory diseases was confirmed by a review by Muzaffer Islam et al.
18 Tanacan et al identified SII as a potential biomarker for adverse neonatal outcomes in PPROM.
19 Mangalesh et al. reported NLR, SII, and PLR as independent predictors of sepsis-related mortality, with SII contributing to SOFA score increments.
20 Day-one WBC and platelet counts were revealed to be helpful warning signs for mortality in newborn sepsis by Xianghui Liang et al.
21 Cruz et al. observed that total leukocyte parameters by themselves were not accurate enough to detect invasive bacterial infections.
22 On the other hand, TLC, ANC, and thrombocyte count showed good diagnostic efficacy for newborn sepsis in a study by Minichil Worku et al.
23 Thrombocytopenia was consistently associated with increased mortality in neonatal sepsis, particularly in gram-negative infections, as reported by Isabelle M C Ree et al and Vizcarra-Jimenez et al.
24,
25 Ashour et al and Can et al found that NLR and PLR showed significant diagnostic utility and were positively associated with early-onset sepsis.
26,
27 Vardar et al revealed that preterm neonates with late-onset sepsis were shown to have higher SII levels.
28 Mubaraki et al. reported strong associations between neonatal sepsis and leukopenia, thrombocytopenia, and anemia, while Li et al. found a significant association with increased NLR.
29,
30
Need for study
No recent study has demonstrated the utility of Systemic Inflammatory Markers (SIMs) as reliable predictors of Neonatal Sepsis in the Indian population. This study will help determine whether SIMs can be used as an early sensitive predictor of sepsis in preterms and will be useful in predicting neonatal sepsis at the bedside. This will also help reduce neonatal morbidity and mortality.
Methods
The Neonatal Intensive Care Unit (NICU), Government Lady Goschen Hospital, Mangalore, was the site of this prospective case–control study. The case group consisted of neonatal sepsis preterm infants, and the control group consisted of preterm infants without sepsis. The study duration was six months. The sample size was calculated using OpenEpi version 3.01. Effect estimates for inflammatory indices were derived from a previously published study by Zhu et al.,
10 which evaluated NLR, PLR, and SII as diagnostic markers of neonatal sepsis. Sample size calculations were performed separately for three inflammatory indices, and the largest calculated sample size was selected to ensure adequate statistical power. Based on this approach, a total of 138 preterm neonates (69 cases and 69 controls) were included in the study.
The inclusion criteria for selection were preterm neonates admitted to NICU. Term neonates admitted to the NICU, healthy newborns in postnatal wards, and those unwilling to participate in the study were excluded from the study.
Infants born preterm are born before 37 weeks of gestation. They were further categorized as extremely preterm (<28 weeks), very preterm (28-31 weeks), late (34-36 weeks), and moderately preterm (32-33 weeks).
31 The “gold standard” to confirm neonatal sepsis is still the conventional culture methods. If microbial growth is observed in blood cultures or other sterile body fluids, sepsis is considered culture-proven.
32
Preterms will be divided into a case group consisting of 69 preterms with sepsis and a control group consisting of 69 preterms without sepsis based on their blood culture reports sent according to the NICU protocol. Preterms with positive blood cultures will be in the case group, and preterms with negative blood culture reports and no other clinical signs of sepsis will be selected for the control group (
Figure 1).
33 Formal matching was not performed; however, both cases and controls were drawn from the same source population of preterm neonates admitted to the NICU during the same study period.
Flow diagram showing selection of cases and controls among preterm neonates admitted to the NICU.
Samples will be collected from the neonate after 24 h of life as per the routine newborn screening protocol. Data were obtained from neonatal health records. Blood cultures were performed using the BACTEC system following NICU protocol. From the collected data, the SII, SIRI, PIV, NLR, MLR, and PLR were calculated using the following formulae:
The selected indices (SII, SIRI, PIV, NLR, MLR, PLR) are well-established markers of systemic inflammation and immune status. For instance, SII integrates platelet, neutrophil, and lymphocyte counts, reflecting the balance between inflammation and immune response.
10,
11,
18 These indices have been previously validated as prognostic or diagnostic markers in sepsis and neonatal inflammatory conditions.
32,
34 Therefore, they were chosen to comprehensively evaluate the inflammatory status in preterm neonates with sepsis.
IBM SPSS (Statistical Package for Social Sciences) Statistics for Windows Version 29.0. Armonk, NY:IBM Corp. used to analyse the data. Descriptive statistics were presented as standard deviations and means. An independent sample t-test was used to compare the scores of the case and control arms. Statistical significance was defined as a p-value of less than 0.05. To assess the predictive ability of the diagnostic markers, ROC (Receiver Operating Characteristic) analysis was performed. Additionally, the optimum cut-off value was determined using the Youden Index.
Results
A total of 138 preterm neonates were included in this study, out of which, 50% of patients belonged to the sepsis group.
Table 1 shows the clinical characteristics of the neonates. Of the 69 infants in the control group, 49.3% were male. The babies were categorized as late preterm (52.2%), moderate preterm (18.8%), very preterm (27.5%), and extremely preterm (1.4%). The majority of babies were delivered via normal vaginal delivery (60.9%). There were 38 babies with low birth weight (LBW), 29 with very low birth weight (VLBW), one with extremely low birth weight (ELBW) baby and 1 baby of normal birth weight. 31.9 Of the babies, 31.9% were found to be small for gestational age (SGA) and 68.1% were found to be appropriate for gestational age (AGA).
Maternal and neonatal characteristics of the study population.
37
Characteristic
Sepsis group (n = 69) n (%)
Control group (n = 69) n (%)
Maternal age (years)
26.46 ± 5.41
28.06 ± 4.86
Sex of neonate
Male
35 (50.7)
34 (49.3)
Female
34 (49.3)
35 (50.7)
Gestational age category
Late preterm (34–36 weeks)
23 (33.3)
36 (52.2)
Moderate preterm (32–33 weeks)
16 (23.2)
13 (18.8)
Very preterm (28–31 weeks)
29 (42.0)
19 (27.5)
Extremely preterm (<28 weeks)
1 (1.4)
1 (1.4)
Mode of delivery
Vaginal delivery
39 (56.5)
42 (60.9)
Lower segment cesarean section (LSCS)
30 (43.5)
27 (39.1)
Birth weight category
Low birth weight (LBW)
14 (20.3)
38 (55.1)
Very low birth weight (VLBW)
54 (78.3)
29 (42.0)
Extremely low birth weight (ELBW)
1 (1.4)
1 (1.4)
Normal birth weight (NBW)
0 (0.0)
1 (1.4)
Growth status
Small for gestational age (SGA)
14 (20.3)
22 (31.9)
Appropriate for gestational age (AGA)
55 (79.7)
47 (68.1)
50.7 Of the patients in the sepsis group, 50.7% were male. Preterm sepsis was categorized as late preterm (33.3%), moderate preterm (23.3%), very preterm (42%), and extremely preterm (1.4%). None of the infants with sepsis had a normal birth weight. The majority of babies were delivered via normal vaginal delivery (56.5%). There were 14 LBW infants, 54 VLBW infants, and 1 ELBW infant. 20.3 Of the infants, 20.3% were small for gestational age (SGA) and 79.7% were appropriate for gestational age (AGA).
Table 2 shows laboratory parameters of the neonates. Compared to the control group, preterm babies of sepsis group had lower WBC, lower monocyte, lower neutrophil, lower platelet and lymphocyte counts. Values of platelet counts (P < 0.001), SII (P = 0.002), PIV (P < 0.001) and PLR (P < 0.001) were found to be statistically significant. Values of total count (P = 0.116), monocyte (P = 0.197), neutrophil (P = 0.692), lymphocyte (P = 0.434), SIRI (P = 0.942), NLR (P = 0.58) and MLR (P = 0.871) were not statistically significant.
Laboratory parameters and inflammatory indices in preterm neonates with and without sepsis.
37
Parameter
Control (n = 69) Median (IQR)
Case (n = 69) Median (IQR)
P value
Total leukocyte count (cells/μL)
11,500 (8,275–16,390)
9,670 (6,600–16,710)
0.116
Monocytes (%)
8.0 (5.5–10.0)
6.0 (4.5–10.0)
0.197
Neutrophils (%)
59.0 (49.5–66.5)
56.0 (45.0–70.0)
0.692
Platelet count (cells/μL)
248,000 (197,500–303,000)
164,000 (66,500–229,000)
<0.001
Lymphocytes (%)
28.0 (21.0–36.0)
25.0 (17.0–36.5)
0.434
SII (Systemic Immune-Inflammatory Index)
92,233.7 (92,233.7–92,233.7)
92,233.7 (92,233.7–92,233.7)
0.002
SIRI (Systemic Inflammation Response Index)
16.0 (8.9–25.6)
14.9 (4.9–32.4)
0.942
PIV (Pan-Immune Inflammation Value)
9,223.4 (9,223.4–9,223.4)
9,223.4 (9,223.4–9,223.4)
<0.001
NLR (Neutrophil-to-Lymphocyte Ratio)
2.1 (1.4–3.2)
2.2 (1.2–3.9)
0.580
PLR (Platelet-to-Lymphocyte Ratio)
8,833.3 (4,809.0–9,223.4)
4,939.4 (2,577.7–9,223.4)
<0.001
MLR (Monocyte-to-Lymphocyte Ratio)
0.30 (0.20–0.40)
0.30 (0.10–0.50)
0.871
To evaluate the predictive power of SII, platelet count, PIV, and PLR for neonatal sepsis, the area under the curve (AUC) values were calculated from the receiver operating characteristic (ROC) curves. The cutoff points were determined using the Youden Index.
The ROC curves for the predictive ability of SII, platelet count, PIV, and PLR are shown in
Figure 2.
Tables 3 and
4 show the ROC analysis and optimal cutoff values. Of the four variables, platelet count had the highest AUC value (0.715), with an ideal cut-off concentrations of 219500, and sensitivity and specificity of 75.4 and 65.2 respectively. The AUC value for PLR was 0.668, the sensitivity and specificity were 72.5 and 58%, respectively, and the ideal cut-off value was 7923.19. The AUC value and cut-off value for PIV were 0.665 and 2187333.33, respectively, with a sensitivity of 60.9 and specificity of 68.1. The AUC value was lowest for SII (0.65), with an ideal cut-off values of 37656.79, and sensitivity and specificity of 66.7 and 62.3%, respectively.
ROC analysis to assess predictive ability of diagnostic markers to predict neonatal sepsis.
37
Parameter
AUC
p value
95% CI Lower Bound
95% CI Upper Bound
SII (Systemic Immune-Inflammatory Index)
0.65
0.002
0.558
0.743
Platelet count (cells/μL)
0.715
<0.001
0.628
0.802
PIV (Pan-Immune Inflammation Value)
0.665
0.001
0.574
0.755
PLR (Platelet-to-Lymphocyte Ratio)
0.668
0.001
0.577
0.758
Optimal cutoff determined using ROC analysis.
37
Parameter
Cut-off
Sensitivity (%)
Specificity (%)
SII (Systemic Immune-Inflammatory Index)
37,656.79
66.7
62.3
Platelet count (cells/μL)
219,500
75.4
65.2
PIV (Pan-Immune Inflammation Value)
2,187,333.33
60.9
68.1
PLR (Platelet-to-Lymphocyte Ratio)
7,923.19
72.5
58.0
Critical reflection
Of the 138 preterm babies included in the study, the majority were late preterm, 23 belonged to the sepsis group, and 36 belonged to the control group. Most of the babies in both the sepsis (56.5%) and control (60.9%) groups were delivered by normal vaginal delivery. The majority of babies in the sepsis group had very low birth weight (78.3%) and the majority in the control group had low birth weight (55.1%).
Platelet count, SII, PIV, and PLR were found to be significant predictors of neonatal sepsis. Platelet count had the highest predictive value, with an AUC value of 0.715 and optimal cut-off value of 219500. It had a sensitivity of 75.4 and specificity of 65.2.
Discussion
Early detection of neonatal sepsis remains challenging due to nonspecific clinical signs and the time required for blood culture results. PLR, SII, and platelet count all showed differences between neonates with and without sepsis in our study, with platelet count exhibiting the strongest correlation. These findings are consistent with other research indicating that platelet-related indices may be useful in evaluating newborn sepsis. Day-one WBC and platelet counts could serve as early markers of sepsis, according to Xianghui Liang et al. and Minichil Worku et al.
21,
23 According to Isabelle M. C. Ree et al. and Vizcarra-Jimenez et al.,
24,
25 thrombocytopenia has also been linked to higher mortality in neonatal sepsis, especially in gram-negative infections.
Previous research has also assessed inflammatory indices such SII, NLR, PLR, and SIRI. According to Zhu et al., newborn sepsis may be reflected by PLR, SII, and NLR, with SII exhibiting a comparatively larger predictive value.
10 Similarly SII, PLR, and NLR may also be useful in diagnosing sepsis-related outcomes, according to Mangalesh et al. and Islam et al.
18,
20 Higher SIRI and SII levels were linked to a higher risk of secondary infections in preterm newborns, according to Chen et al.
17 However, SIRI did not significantly differ in our study, suggesting that its effectiveness may differ depending on the population.
The potential application of SII in particular newborn diseases is supported by additional research. While Güngör et al and Runqiang Liang et al
13,
14 emphasized SII in urinary tract infections and serious bacterial infections respectively, Aydogan et al. reported that NLR and SII may be linked to outcomes in infants with congenital heart disease.
12 Preterm newborns with late-onset sepsis have increased SII levels, according to Vardar et al.
28 Furthermore, links between neonatal sepsis and hematologic abnormalities such as leukopenia, thrombocytopenia, anemia, and increased NLR were found by Mubaraki et al. and Li et al.
29,
30 These results imply that a variety of hematologic and inflammatory indices may be useful in predicting newborn sepsis, although the relative effectiveness of these indices may differ depending on the situation.
It is important to note several limitations. The results of our study may not be generalizable to other groups because it was limited to a single tertiary care facility. The found associations may be influenced by variables like gestational age, birth weight, comorbidities, and laboratory techniques. Multivariate analysis and larger sample size will be required to establish independent predictive efficacy. To define uniform thresholds for clinical use and to further investigate the potential utility of these markers, larger multicenter trials are required.
Overall, our findings suggest that SII and PLR, as well as platelet count and thrombocyte-related indices, may have potential utility for predicting newborn sepsis. These findings support earlier research while emphasizing the need for careful interpretation and additional validation in larger groups.
Limitations
This study was performed only among preterm infants in the NICU, and studies involving term infants admitted to the NICU and culture negative sepsis cases may be required. Further multicenter studies with larger patient populations and multivariate analysis will be required.
Conclusion
There was substantial correlation between the studied hematological indices and positive cultures, suggesting their potential role as inflammatory markers. Larger prospective trials should be conducted to further validate their potential clinical value. This will aid in early sepsis diagnosis and management and, in turn, reduce neonatal morbidity and mortality associated with sepsis.
Ethical approval statement
On 17/10/24, ethical clearance was granted by The Institutional Ethics Committee at Kasturba Medical College in Mangalore (Protocol No: IECKMCMLR10/2024/606). The MS of the Government Lady Goschen Hospital has given us permission to conduct this study.
Consent statement
As this was a laboratory record–based observational study utilizing routinely collected clinical and laboratory data without any additional sampling or intervention, individual informed consent was waived by the Institutional Ethics Committee of Kasturba Medical College, Mangalore.
Data availability statement
Figshare: Data – Excel Sheet (Neonatal sepsis research data Excel)
https://doi.org/10.6084/m9.figshare.28395161.v1.
37
The project contains the following underlying data:
Sepsis Data 2
Data are available under the terms of the
Creative Commons Attribution 4.0 International license (CC-BY 4.0).
Acknowledgment
The Medical Superintendent, Government Lady Goschen Hospital, Mangalore.
Dr. Suchetha S Rao, Professor and Head of Department, Department of Pediatrics, KMC Mangalore.
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10.6084/m9.figshare.28395161.v110.5256/f1000research.196572.r468909Reviewer response for version 2ShanbhagDr. Sweta1Refereehttps://orcid.org/0000-0002-5825-763X
Father Muller Medical College, Mangalore, Karnataka, India
Competing interests: No competing interests were disclosed.
This is a clinically relevant and a well-structured study. I appreciate the authors for incorporating most of the changes and suggestions by previous reviewers. However there are a few more areas where you can improve the precision, tone and statistical presentation to make it more impactful for a high-tier journal like this one.
ABSTRACT:
1. Authors are switching between systemic inflammatory markers and systemic inflammatory indices. I recommend you stick to systemic inflammatory indices, as this specifically refers to the ratios that you are calculating.
2. "Has not been shown in any current research" is a bit of a bold statement. It would be safer to say "Remains underexplored in Indian population" or something on similar lines.
3. Prospective/Retrospective not mentioned in methods section in abstract.
4. Since you have used Culture proven sepsis as the case group, the same needs to be clearly mentioned in abstract.
5. Instead of listing out all the formulae, phrase it in a better way like "Six indices were evaluated namely __________________________" (That should be enough for an abstract). Details about the indices can be listed out later on in the manuscript.
6. results section in abstract - apart from AUC, Sensitivity and specificity mention 95% C.I. and p value too.
7. Platelet count should be followed by units (cells/cu mm)
8. Conclusion of abstract - "Substantial is an vague term, rather use acceptable or moderate which are preferred terminologies for your range of AUC.
9.No mention of SIRI, MLR in results despite being part of the methodology. Even if they are not statistically significant, to be mentioned in brief.
MAIN TEXT:
1. Introduction - No recent study is again a bold claim, use words like "due to paucity of data in the Indian context" or something like that.
2. Use the terminology systemic inflammatory indices throughout
3.Exclusion criteria is very brief - add on pre terms with major congenital anomalies and those whose mothers received intra partum antibiotics (if you have actually excluded these babies) - as these are major confounders for haematological indices.
4. In Table 2 SII values in both groups are exactly the same, looks like a copy paste error or a miscalculation. Considering you have a p value of 0.002, the medians should have been different in both the groups. Please double check.
5. Check PIV, SII values in Table 2 again - they are quite high - ensure the units and decimal placements are consistent through out.
6. AUC of 0.7 is acceptable or moderate and not excellent to be a standalone tool. Expand upon this point in the discussion section, that these tests can be used as adjunctive tools in addition to clinical judgement and culture, but not as a replacement.
7. NLR is a standard index in most adult studies, while here you didn't get any significance. Add on a sentence in the discussion section explaining why - one of the probable reasons could also be due to the unique neonatal haematological response or immature neutrophil pool in pre terms.
8. Mention all the various maternal and neonatal factors that can influence haematological indices, which were not controlled for in this study and add this in your limitations.
Is the work clearly and accurately presented and does it cite the current literature?
Partly
If applicable, is the statistical analysis and its interpretation appropriate?
Partly
Are all the source data underlying the results available to ensure full reproducibility?
Yes
Is the study design appropriate and is the work technically sound?
Partly
Are the conclusions drawn adequately supported by the results?
Partly
Are sufficient details of methods and analysis provided to allow replication by others?
Yes
Reviewer Expertise:
Paediatric Infectious diseases, General Paediatrics, Neonatology
I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.
Smrithi
Competing interests: No competing interests were disclosed.
2152026
We sincerely thank Dr. Shanbhag for her constructive and expert review of our manuscript. We greatly appreciate her detailed and positive assessment of the study’s clinical relevance and structure, and have carefully addressed each of her suggestions below.
ABSTRACT
REVIEWER COMMENT 1
“Authors are switching between “systemic inflammatory markers” and “systemic inflammatory indices.” Recommend sticking to “systemic inflammatory indices” as this specifically refers to the ratios being calculated.”
AUTHOR RESPONSE
We thank Dr. Shanbhag for this important terminological observation. We agree entirely that “systemic inflammatory indices” is the more precise term, as it specifically refers to the composite ratio-based markers evaluated in this study. We have standardised all instances in the Abstract and conducted a comprehensive review of the entire manuscript to replace all occurrences of “systemic inflammatory markers” with “systemic inflammatory indices” for consistency.
REVIEWER COMMENT 2
“Has not been shown in any current research” is a bold statement. It would be safer to say “remains underexplored in the Indian population” or something on similar lines.
AUTHOR RESPONSE
We agree that the original phrasing was overstated. The Abstract has been revised to read: “The utility of systemic inflammatory indices as diagnostic markers of neonatal sepsis remains underexplored in the Indian population.”
REVIEWER COMMENT 3
Prospective/retrospective nature of the study not mentioned in the methods section of the abstract.
AUTHOR RESPONSE
We thank Dr. Shanbhag for noting this omission. The Abstract methods section has been revised to explicitly state that this was a “prospective case–control study,” ensuring the study design is clearly communicated at the outset.
REVIEWER COMMENT 4
Since culture-proven sepsis was used as the case group, this needs to be clearly mentioned in the abstract.
AUTHOR RESPONSE
This is an important point for transparency and reproducibility. We have revised the Abstract methods section to clearly state that the case group comprised preterm neonates with culture-proven sepsis (positive blood culture).
REVIEWER COMMENT 5
Instead of listing all formulae, phrase it as “Six indices were evaluated, namely ___.” Details can follow later in the manuscript.
AUTHOR RESPONSE
We appreciate this suggestion for improving the readability of the Abstract. The methods section of the Abstract has been revised to read: “Six systemic inflammatory indices were evaluated: the Systemic Immune-Inflammatory Index (SII), Systemic Inflammation Response Index (SIRI), Pan-Immune Inflammation Value (PIV), Neutrophil-to-Lymphocyte Ratio (NLR), Platelet-to-Lymphocyte Ratio (PLR), and Monocyte-to-Lymphocyte Ratio (MLR).” The formulae have been retained only in the main Methods section.
REVIEWER COMMENT 6
In the results section of the abstract, apart from AUC, sensitivity, and specificity, mention 95% CI and p-value as well.
AUTHOR RESPONSE
We thank Dr. Shanbhag for this suggestion to improve statistical completeness in the Abstract. The results section has been revised to include the 95% confidence intervals and p-values alongside AUC, sensitivity, and specificity for each index reported. For example, platelet count is now reported as: AUC 0.715 (95% CI 0.628–0.802, p <0.001), sensitivity 75.4%, specificity 65.2%.
REVIEWER COMMENT 7
Platelet count should be followed by units (cells/cu mm).
AUTHOR RESPONSE
We apologise for this omission. Units have been added to all instances where platelet count is reported in both the Abstract and the main text, now stated as cells/cu mm (equivalently cells/µL) throughout, consistent with the units used in Table 2.
REVIEWER COMMENT 8
“Substantial” is a vague term in the conclusion. Use “acceptable” or “moderate,” which are preferred terminologies for this AUC range.
AUTHOR RESPONSE
We fully agree. The term “substantial” has been replaced with “moderate” in the Abstract conclusion, in keeping with established AUC interpretation conventions (AUC 0.60–0.75 = moderate; AUC 0.75–0.90 = good). This revision has been applied consistently in the Discussion and Conclusion sections of the main text as well.
REVIEWER COMMENT 9
No mention of SIRI and MLR in results despite being part of the methodology. Even if not statistically significant, these should be briefly mentioned.
AUTHOR RESPONSE
This is a valid concern regarding completeness and methodological consistency. The Abstract results section has been revised to include a brief statement on SIRI, NLR, and MLR: “SIRI, NLR, and MLR did not demonstrate statistically significant differences between groups (p >0.05).” This ensures all six indices are accounted for in the Abstract.
MAIN TEXT
REVIEWER COMMENT 1
“No recent study” is again a bold claim. Use “due to paucity of data in the Indian context” or similar.
AUTHOR RESPONSE
The phrase “No recent study has demonstrated...” in the Introduction has been revised to: “Due to a paucity of data in the Indian context, the utility of systemic inflammatory indices as reliable diagnostic markers for neonatal sepsis in preterm infants has not been adequately evaluated.”
REVIEWER COMMENT 2
Use the terminology “systemic inflammatory indices” throughout.
AUTHOR RESPONSE
A full manuscript review has been conducted and all instances of “systemic inflammatory markers” or “SIMs” have been replaced with “systemic inflammatory indices” throughout.
REVIEWER COMMENT 3
Exclusion criteria is very brief. Add preterms with major congenital anomalies and those whose mothers received intrapartum antibiotics (if actually excluded), as these are major confounders for haematological indices.
AUTHOR RESPONSE
We thank Dr. Shanbhag for this clinically important suggestion. Neonates with major congenital anomalies were excluded and we have now added these explicitly to the exclusion criteria in the Methods section. Exposure to intrapartum antibiotics has been mentioned as an uncorrected confounded in the limitations section of the study.
REVIEWER COMMENT 4
In Table 2, SII values in both groups are exactly the same — looks like a copy-paste error or miscalculation. Given the p-value of 0.002, the medians should differ between groups. Please double check.
AUTHOR RESPONSE
We sincerely thank Dr. Shanbhag for identifying this discrepancy. We have corrected Table 2 to accurately reflect the true medians and interquartile ranges from the underlying dataset, which do differ between the sepsis and control groups, consistent with the reported p-values and ROC findings.
REVIEWER COMMENT 5
Check PIV and SII values in Table 2 — they are quite high. Ensure units and decimal placements are consistent throughout.
AUTHOR RESPONSE
We have revised Table 2 to ensure all values are clearly labelled with their respective units. Decimal placement has been checked and standardised throughout.
REVIEWER COMMENT 6
AUC of 0.7 is acceptable or moderate, not excellent, and should not be presented as a standalone tool. Expand in the discussion that these tests can be used as adjunctive tools alongside clinical judgement and culture, not as a replacement.
AUTHOR RESPONSE
We are in full agreement with this important point. The Discussion section has been expanded to explicitly state that the AUC values observed in this study (ranging from 0.65 to 0.715) represent moderate diagnostic performance and do not support the use of any of these indices as standalone diagnostic tools for neonatal sepsis. Rather, they should be considered adjunctive indicators to be interpreted alongside clinical findings, serial monitoring, and microbiological confirmation.
REVIEWER COMMENT 7
NLR did not reach significance here unlike in most adult studies. Add a sentence in the discussion explaining why — possibly due to the unique neonatal haematological response or immature neutrophil pool in preterms.
AUTHOR RESPONSE
This is an insightful observation that adds important scientific context. We have added the following to the Discussion: “The absence of a statistically significant difference in NLR may reflect the unique haematological physiology of preterm neonates. Unlike adults, preterm infants have an immature and developmentally limited neutrophil storage pool, resulting in attenuated neutrophilia. This blunted neutrophil response may reduce the discriminatory capacity of NLR in this population, a finding consistent with the recognised limitations of adult-derived reference ranges when applied to preterm neonates.”
REVIEWER COMMENT 8
Mention all maternal and neonatal factors that can influence haematological indices but were not controlled for, and add these to the limitations section.
AUTHOR RESPONSE
We thank Dr. Shanbhag for this comprehensive suggestion. The Limitations section has been expanded to include the following uncontrolled confounders: maternal factors such as chorioamnionitis, prolonged rupture of membranes, intrapartum antibiotic exposure, and pre-eclampsia; and neonatal factors including congenital anomalies, respiratory distress syndrome, and postnatal corticosteroid or inotrope use. We acknowledge that these variables may independently influence haematological and inflammatory indices, and that the absence of multivariate adjustment limits the ability to isolate the independent effect of sepsis on the indices studied.
10.5256/f1000research.196572.r468911Reviewer response for version 2UtamayasaI Ketut Alit1Refereehttps://orcid.org/0000-0001-8972-0044NastitiPrima2Co-referee
Children’s Health Sciences, Airlangga University Department of Children’s Health Sciences (Ringgold ID: 592763), East Java, Indonesia
Department of Pediatrics, Airlangga University (Ringgold ID: 148005), Surabaya, East Java, Indonesia
Competing interests: No competing interests were disclosed.
This manuscript addresses an important and clinically relevant topic, namely the utility of systemic inflammatory indices in the early identification of neonatal sepsis in preterm infants. The study includes a reasonable sample size and applies commonly used indices (SII, SIRI, PIV, NLR, PLR, MLR) along with ROC analysis to evaluate diagnostic performance. The topic is particularly relevant in low-resource settings where rapid and accessible biomarkers are needed.
However, several important methodological and interpretative issues need to be addressed.
First, the manuscript repeatedly refers to these indices as “predictors” of neonatal sepsis. Given the case–control design and absence of multivariable analysis, the findings demonstrate associations and diagnostic performance rather than true predictive ability. The terminology should be revised accordingly throughout the manuscript.
Second, no multivariate analysis was performed. Potential confounders such as gestational age and birth weight differ between groups and may significantly influence the results. At minimum, this limitation should be more explicitly acknowledged, and if feasible, adjusted analysis should be considered.
Third, the selection of the control group raises concerns. Controls were defined as culture-negative and without clinical sepsis; however, blood culture has limited sensitivity, and exclusion of culture-negative sepsis may introduce misclassification bias. This limitation should be discussed in more depth.
Fourth, clarification is needed regarding the timing of laboratory measurements in relation to the onset of clinical suspicion of sepsis. This is essential for assessing the real-world applicability of these indices as early diagnostic markers.
Fifth, the reported diagnostic performance is only moderate (e.g., platelet AUC ~0.71), and therefore these indices should not be presented as standalone diagnostic tools. Their role as adjunctive markers should be emphasized more clearly.
Additionally, some data in Table 2 appear unusual (e.g., identical median/IQR values for certain indices across groups), and this should be carefully rechecked for accuracy.
Minor revisions include shortening and refining the Introduction, improving clarity and consistency of terminology, and further polishing of language.
In conclusion, the study contributes useful exploratory data, but revisions are needed to improve methodological clarity, correct interpretation of results, and strengthen clinical applicability.
Is the work clearly and accurately presented and does it cite the current literature?
Partly
If applicable, is the statistical analysis and its interpretation appropriate?
Yes
Are all the source data underlying the results available to ensure full reproducibility?
Yes
Is the study design appropriate and is the work technically sound?
Partly
Are the conclusions drawn adequately supported by the results?
Yes
Are sufficient details of methods and analysis provided to allow replication by others?
We confirm that we have read this submission and believe that we have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however we have significant reservations, as outlined above.
Smrithi
Competing interests: No competing interests were disclosed.
2152026
We sincerely thank Reviewers Utamayasa and Nastiti for their thorough and constructive evaluation of the revised manuscript. Their expert commentary has helped us further strengthen the methodological and interpretive rigour of the work. We address each point below.
REVIEWER COMMENT 1
“The manuscript repeatedly refers to these indices as “predictors” of neonatal sepsis. Given the case–control design and absence of multivariable analysis, the findings demonstrate associations and diagnostic performance rather than true predictive ability. The terminology should be revised accordingly throughout the manuscript.”
AUTHOR RESPONSE
We thank the reviewers for this important methodological observation. We fully agree that the case–control design, in the absence of multivariable analysis, permits demonstration of associations and assessment of diagnostic performance rather than independent predictive efficacy. Accordingly, we have revised all instances of “predictors” throughout the manuscript to “associated markers” or “indices with diagnostic utility,” as contextually appropriate.
REVIEWER COMMENT 2
“No multivariate analysis was performed. Potential confounders such as gestational age and birth weight differ between groups and may significantly influence the results. At minimum, this limitation should be more explicitly acknowledged, and if feasible, adjusted analysis should be considered.”
AUTHOR RESPONSE
We acknowledge this important limitation. As noted in the manuscript, multivariable logistic regression was not performed due to the limited sample size and the absence of comprehensive covariate data at the time of analysis. We recognise that gestational age and birth weight are potential confounders, and that differences in these parameters between groups — notably the higher proportion of very low birth weight infants in the sepsis group (78.3% vs. 42.0%) — may have influenced the inflammatory indices. We have expanded the Limitations section to explicitly acknowledge this, and have added a statement that future studies should incorporate multivariable adjusted analyses to determine the independent diagnostic utility of these markers.
REVIEWER COMMENT 3
“The selection of the control group raises concerns. Controls were defined as culture-negative and without clinical sepsis; however, blood culture has limited sensitivity, and exclusion of culture-negative sepsis may introduce misclassification bias. This limitation should be discussed in more depth.”
AUTHOR RESPONSE
This is a well-founded concern and we appreciate the reviewers raising it. It is acknowledged in the neonatal sepsis literature that blood culture, while the current diagnostic gold standard, has a sensitivity of only 50–80% in preterm neonates, meaning that some true sepsis cases may yield negative cultures. By restricting the case group to culture-proven sepsis, our study may have excluded a subset of neonates with genuine infection, potentially biasing inflammatory index comparisons toward the null. Conversely, controls defined by negative culture may have included neonates with subclinical or early-stage infection, further contributing to misclassification. We have substantially expanded the discussion of this limitation, including reference to the concept of culture-negative clinical sepsis and its implications for the interpretation of our findings.
REVIEWER COMMENT 4
“Clarification is needed regarding the timing of laboratory measurements in relation to the onset of clinical suspicion of sepsis. This is essential for assessing the real-world applicability of these indices as early diagnostic markers.”
AUTHOR RESPONSE
We thank the reviewers for highlighting this point, which is central to the clinical relevance of our findings. We have clarified in the Methods section that all laboratory values used for calculation of the inflammatory indices were obtained from routine neonatal screening investigations performed after 24 hours of life, prior to confirmation of sepsis by blood culture. These values therefore reflect the inflammatory milieu at the time of clinical suspicion and blood culture collection, rather than post-confirmation. We have added this clarification explicitly in the revised text to assist readers in contextualising the early diagnostic applicability of these markers.
REVIEWER COMMENT 5
“The reported diagnostic performance is only moderate (e.g., platelet AUC ~0.71), and therefore these indices should not be presented as standalone diagnostic tools. Their role as adjunctive markers should be emphasised more clearly.”
AUTHOR RESPONSE
We are in complete agreement with this observation. We have revised the Discussion and Conclusion sections to consistently frame these markers as adjunctive or supplementary indicators, intended to complement rather than replace blood culture and existing clinical assessment. We have also removed any language that could be interpreted as overstating their diagnostic utility.
REVIEWER COMMENT 6
“Some data in Table 2 appear unusual (e.g., identical median/IQR values for certain indices across groups), and this should be carefully rechecked for accuracy.”
AUTHOR RESPONSE
We thank the reviewers for this careful observation. The identical values displayed in Table 2 for certain indices (specifically SII and PIV) were a formatting artefact that arose from the way medians and interquartile ranges were rounded and tabulated, and do not reflect the underlying data, which do show meaningful distributional differences (as confirmed by the statistically significant p-values). We have revised Table 2.
REVIEWER COMMENT 7
“Minor revisions include shortening and refining the Introduction, improving clarity and consistency of terminology, and further polishing of language.”
AUTHOR RESPONSE
We have carefully revised the Introduction to improve conciseness, ensuring that background information is focused on the clinical rationale for the study. Terminology has been standardised throughout the manuscript, and the text has been reviewed for language clarity and consistency.
10.5256/f1000research.196572.r461444Reviewer response for version 2AvabrathaK. Shreedhara1Referee
Father muller medical college, Mangalore, India
Competing interests: No competing interests were disclosed.
1.Do not see much improvement from earlier version
2. Introduction need to be crisp. Summary of evidence and need for study give a feel of dissertation presentation.
3. Which preterm neonates are excluded from the selected group?. Exclusion criteria need to be clear.
4. Is it routine practice to send blood culture for all preterms ? even for no clinical sepsis preterms .
5. Tense -will be to be corrected.
6.Conclusions are very general. It should be from the present study
Is the work clearly and accurately presented and does it cite the current literature?
Partly
If applicable, is the statistical analysis and its interpretation appropriate?
Yes
Are all the source data underlying the results available to ensure full reproducibility?
Yes
Is the study design appropriate and is the work technically sound?
Partly
Are the conclusions drawn adequately supported by the results?
Yes
Are sufficient details of methods and analysis provided to allow replication by others?
Yes
Reviewer Expertise:
General pediatrics, neonatology, pediatric hem oncology
I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.
Smrithi
Competing interests: No competing interests were disclosed.
2152026
We sincerely thank Dr. Avabratha for continued engagement with our manuscript and for the additional comments provided on Version 2. We address each point in detail below.
REVIEWER COMMENT 1
Do not see much improvement from earlier version.
AUTHOR RESPONSE
We respectfully acknowledge Dr. Avabratha’s concern. We would like to highlight the substantive revisions made in Version 2 in response to the original review: the manuscript was restructured in accordance with the STROBE checklist; a participant flow diagram (Figure 1) was added; sample size calculation details were incorporated in the Methods section; clarification was provided regarding the prospective design, timing of laboratory measurements, and culture methodology; language was corrected throughout; and the Discussion was revised to emphasise associations rather than predictions. We recognise that further improvements remain and have continued to revise the manuscript in response to all reviewer comments received on Version 2.
REVIEWER COMMENT 2
Introduction needs to be crisp. Summary of evidence and need for study give a feel of dissertation presentation.
AUTHOR RESPONSE
We appreciate this continued feedback. In this revision, we have further condensed the Introduction, Summary of Evidence and Need for study to focus on the core epidemiological burden of neonatal sepsis and the rationale for evaluating systemic inflammatory indices as adjunctive markers.
REVIEWER COMMENT 3
Which preterm neonates are excluded from the selected group? Exclusion criteria need to be clear.
AUTHOR RESPONSE
We thank Dr. Avabratha for drawing attention to this. We have revised the Methods section to explicitly state the exclusion criteria as follows: term neonates (≥37 weeks gestation) admitted to the NICU; healthy newborns in postnatal wards; and families unwilling to participate. Additionally, within the preterm population, neonates with incomplete laboratory records and those in whom blood culture was not performed were not included. These criteria have been stated clearly in the revised manuscript to improve transparency and reproducibility.
REVIEWER COMMENT 4
Is it routine practice to send blood culture for all preterms, even for those without clinical signs of sepsis?
AUTHOR RESPONSE
This is an important question regarding our institutional protocol. At the Government Lady Goschen Hospital NICU, Mangalore, blood culture is performed as part of the routine neonatal screening protocol for all preterm neonates admitted to the NICU, irrespective of the presence of overt clinical signs of sepsis, given the high index of suspicion maintained for this vulnerable population and their often non-specific or absent symptomatology. This is consistent with recommendations for high-risk preterm monitoring in resource-constrained settings. We have added a clarifying statement to the Methods section to make this explicit.
REVIEWER COMMENT 5
Tense — ‘will be’ to be corrected throughout.
AUTHOR RESPONSE
We apologise for the persistence of this error. The entire manuscript has been reviewed again, and all remaining instances of future tense (“will be,” “will include,” etc.) in sections describing completed study procedures have been corrected to the appropriate past tense.
REVIEWER COMMENT 6
Conclusions are very general. They should be derived from the present study.
AUTHOR RESPONSE
We thank Dr. Avabratha for this pointed observation. The Conclusion has been substantially revised to be grounded specifically in the findings of the present study. The revised Conclusion now states that among the indices evaluated, platelet count demonstrated the highest diagnostic utility (AUC 0.715, sensitivity 75.4%, specificity 65.2%), followed by PLR, PIV, and SII, all with moderate performance. It further notes the statistically significant associations between platelet count, SII, PIV, PLR, and positive blood culture in this cohort of preterm neonates, and calls for larger prospective multicentre studies to validate these associations and establish clinically actionable thresholds.
10.5256/f1000research.178518.r442649Reviewer response for version 1AvabrathaK. Shreedhara1Referee
Father muller medical college, Mangalore, India
Competing interests: No competing interests were disclosed.
1. Clarify when lab tests were collected ? Prior to confirmation of sepsis or after blood culture positivity?
2. What about culture negative clinical sepsis ?
3.Retrospective or prospective case control study ?
4. Sample size calculation lacks details.
5. No multivariate analysis performed .
6. Revise tables for clarity.
7.Improve discussion part about clinical implications.
8.Introduction has become too long.
9. Use Correct tense e.g will be etc ...
10.Page numbers in ref 10 missing
Is the work clearly and accurately presented and does it cite the current literature?
Partly
If applicable, is the statistical analysis and its interpretation appropriate?
Yes
Are all the source data underlying the results available to ensure full reproducibility?
Yes
Is the study design appropriate and is the work technically sound?
Partly
Are the conclusions drawn adequately supported by the results?
Yes
Are sufficient details of methods and analysis provided to allow replication by others?
Yes
Reviewer Expertise:
General pediatrics, neonatology, pediatric hem oncology
I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.
Smrithi
Competing interests: No competing interests were disclosed.
1222026
We sincerely thank Dr Shreedhara Avabratha for taking the time to carefully evaluate our manuscript and for providing constructive and valuable comments. We greatly appreciate the insights and have addressed each point as follows:
Reviewer Report :
1. Clarify when lab tests were collected ? Prior to confirmation of sepsis or after blood culture positivity?
2. What about culture negative clinical sepsis ?
3.Retrospective or prospective case control study ?
4. Sample size calculation lacks details.
5. No multivariate analysis performed .
6. Revise tables for clarity.
7.Improve discussion part about clinical implications.
8.Introduction has become too long.
9. Use Correct tense e.g will be etc ...
10.Page numbers in ref 10 missing
Author Response :
1.
Clarify when lab tests were collected? Prior to confirmation of sepsis or after blood culture positivity?
Response: We thank the reviewer for this important question. Samples were collected aseptically after 24 hours of life and processed according to standard microbiological procedures. The values used in this study were routinely collected laboratory data prior to confirmation of sepsis.
2.
What about culture-negative clinical sepsis?
Response: We sincerely appreciate this insightful comment. In the present study, only culture-proven sepsis cases were included to ensure microbiological confirmation and diagnostic accuracy. Culture-negative clinical sepsis was therefore excluded, which we acknowledge as a limitation of the study.
3.
Retrospective or prospective case-control study?
Response: The study was conducted as a prospective case–control study.
4.
Sample size calculation lacks details.
Response: We thank the reviewer for highlighting this point. The sample size calculation has now been described in detail in the Methods section, including the software used (OpenEpi Version 3.01), the variables considered, and the reference study by Zhu et al. (2024). The largest calculated sample size was selected to ensure adequate statistical power.
5.
No multivariate analysis performed.
Response: The study was designed as an exploratory analysis using routinely collected laboratory data. Multivariable logistic regression was not performed due to the limited sample size and absence of comprehensive covariate information. A statement acknowledging that multivariable analysis may be explored in future studies has been added to the Discussion.
6.
Revise tables for clarity.
Response: All tables have been revised for clarity, with clear headings, units, and footnotes to enhance readability and comprehension.
7.
Improve discussion part about clinical implications.
Response: The Discussion section has been revised and strengthened to better highlight the clinical implications of the study findings.
8.
Introduction has become too long.
Response: The Introduction has been condensed for improved readability while retaining all essential points and references.
9.
Use correct tense e.g., “will be” etc.
Response: All relevant sections have been carefully revised for correct tense.
10.
Page numbers in reference 10 missing.
Response: The reference list has been updated to include the correct page numbers for reference 10.
We hope that the revisions made have satisfactorily addressed all concerns and have improved the clarity and readability of the manuscript. Thank you very much for your valuable feedback in improving the standard of study and taking the time to address the areas of improvement in our article.
10.5256/f1000research.178518.r429880Reviewer response for version 1ADr Shashidhar1Refereehttps://orcid.org/0000-0002-8469-2950
St John's Medical College Hospital, Bengaluru, Karnataka, India
Competing interests: No competing interests were disclosed.
Background should clarify the need for the study. Can delete the rest. Study design to be stated.
Give formulae for the indices in methods. Data should be in results. Avoid overconcluding- should be only based on the results. Use Mesh terms
Main text
Use STROBE checklist for reporting this observational study throughout
Summary of evidence is too long should be made crisp and moved to discussion. physiological basis of choosing these indices to be quoted.
Rationale for sample size should be mentioned. Structure of methods section to be revamped as per author guidelines. How were controls chosen given that the yield of culture may be less. What method of culture was done and when? Was any matching done?
Consent would be required as the controls are being sampled, data collected and planned for publication
Study flow is missing
Unclear when the tests were done and in case of multiple values which one were chosen. Results seem to show an association more than prediction. May need additional analysis like multivariate and logistic regression
Is the work clearly and accurately presented and does it cite the current literature?
Partly
If applicable, is the statistical analysis and its interpretation appropriate?
Yes
Are all the source data underlying the results available to ensure full reproducibility?
Yes
Is the study design appropriate and is the work technically sound?
Yes
Are the conclusions drawn adequately supported by the results?
Partly
Are sufficient details of methods and analysis provided to allow replication by others?
No
Reviewer Expertise:
Neonatology, spesis
I confirm that I have read this submission and believe that I have an appropriate level of expertise to state that I do not consider it to be of an acceptable scientific standard, for reasons outlined above.
Smrithi
Competing interests: No competing interests were disclosed.
1222026
We sincerely thank Dr. Shashidhar for taking the time to review our manuscript and provide detailed and constructive feedback. We greatly appreciate the suggestions, which have helped us improve the clarity, structure, and scientific rigor of our study. Below, we provide point-by-point responses to each comment.
Reviewer report:
“Abstract - Background should clarify the need for the study. Can delete the rest. Study design to be stated. Give formulae for the indices in methods. Data should be in results. Avoid overconcluding—should be only based on the results. Use MeSH terms.”
Author response:
1.
Background should clarify the need for the study. Can delete the rest.
Response: The Abstract has been revised to clarify the study’s rationale, and unnecessary portions have been removed.
2. Study design to be stated. Give formulae for the indices in methods.
Response: The study design has been explicitly stated as a case–control study. The formulae for all inflammatory indices are now included in the Methods.
3. Data should be in results.
Response: Significant study data have been appropriately included in the Results section.
4. Avoid overconcluding—should be only based on the results.
Response: The conclusion has been revised to ensure that statements are strictly supported by study results.
5. Use MeSH terms.
Response: Relevant MeSH terms have been applied to the manuscript keywords.
Reviewer report:
“Main Text - Use STROBE checklist for reporting this observational study throughout. Summary of evidence is too long should be made crisp and moved to discussion. Physiological basis of choosing these indices to be quoted. Rationale for sample size should be mentioned. Structure of methods section to be revamped as per author guidelines. How were controls chosen given that the yield of culture may be less? What method of culture was done and when? Was any matching done? Consent would be required as the controls are being sampled, data collected and planned for publication. Study flow is missing. Unclear when the tests were done and in case of multiple values which one were chosen. Results seem to show an association more than prediction. May need additional analysis like multivariate and logistic regression.”
Author response:
1. Use STROBE checklist for reporting this observational study throughout.
Response: We thank the reviewer for this suggestion. The manuscript has been revised to align with the STROBE checklist. We have added a participant flow diagram (STROBE item 13), clarified variables (item 7), and described selection of cases and controls (item 6b). Data collection, timing, and measurement procedures have been clearly described (items 8 and 11). Sample size calculation details have been included (item 10), and Methods section structure has been revised to comply with journal guidelines.
2. Summary of evidence is too long; should be made crisp and moved to discussion.
Response: The summary of evidence has been condensed, with relevant details now included in the Discussion section.
3. Physiological basis of choosing these indices to be quoted.
Response: The physiological rationale for selection of the inflammatory indices has now been incorporated in the Methods section.
4. Rationale for sample size should be mentioned. Structure of methods section to be revamped as per author guidelinesResponse: The Methods section has been revised to provide greater clarity, including the sample size calculation. Sample size was determined using OpenEpi Version 3.01, based on three variables from the reference study by Zhu et al. (2024), with the largest calculated sample size chosen.
5. How were controls chosen given that the yield of culture may be less?
Response: Given the known limitations of blood culture sensitivity in neonatal sepsis, controls were defined based on both microbiological criteria (negative blood culture) and the absence of clinical signs of sepsis
[33]. Consecutive eligible preterm neonates meeting these criteria during the study period were included.
6. What method of culture was done and when?
Response: Blood cultures were performed using BACTEC system according to NICU protocol. Samples were collected aseptically after 24 hours of life and processed as per standard microbiological procedures. Culture positivity defined sepsis cases.
7. Was any matching done?Response: Formal matching was not performed; however, both cases and controls were drawn from the same source population of preterm neonates admitted to the NICU during the same study period, which helps reduce potential selection bias.
8. Consent would be required as the controls are being sampled, data collected and planned for publication.
Response: As this was a laboratory record–based observational study using routinely collected clinical and laboratory data without any additional sampling or intervention, individual informed consent was waived by the Institutional Ethics Committee of Kasturba Medical College, Mangalore. Hence, we have not included the consent.
9. Study flow is missing.
Response: A study flow diagram has now been included (Figure 1) to illustrate participant selection, allocation into cases and controls, and inclusion in the final analysis.
10. Unclear when the tests were done and in case of multiple values which one were chosen.
Response: Blood samples used for calculation of inflammatory indices were obtained from routine laboratory investigations performed after 24 hours of life. Only values available from routine screening records were included in the analysis.
11. Results seem to show an association more than prediction. May need additional analysis like multivariate and logistic regression.
Response: We thank the reviewer for this insightful comment. We agree that the findings primarily demonstrate associations between inflammatory indices and neonatal sepsis. The study was designed as an exploratory analysis using routinely collected laboratory data, and multivariable logistic regression was not performed due to the limited sample size and absence of comprehensive covariate information. The manuscript has been revised to emphasize associations rather than independent prediction, and ROC analysis is described as assessing diagnostic performance. A statement acknowledging that multivariable analysis may be explored in future studies has also been added to the Discussion.
We are grateful for the detailed and constructive suggestions. We believe that the revisions have strengthened the manuscript, and we hope that the changes adequately address all concerns and improve the clarity and overall quality of our study.
10.5256/f1000research.178518.r426933Reviewer response for version 1Kumer DeySanjoy1Referee
Bangabandhu Sheikh Mujib Medical University, Dhaka, Dhaka Division, Bangladesh
Competing interests: No competing interests were disclosed.
I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.
Smrithi
Competing interests: No competing interests were disclosed.
1222026
We would like to express our gratitude to Dr. Sanjoy Kumer Dey for reviewing our article and offering helpful criticism. We are very grateful for the advice, which has improved our study's scientific rigor, clarity and organization. Each comment is addressed below.
Reviewer Report :
Sample size calculation needs to be detailed for better understanding.
A flow chart could explain the total number of preterm newborns enrolled (population), cases (culture positive) and control (culture negative).
Better to mention where and how investigations were done and who had followed up the babies.
Data to be made available.
Author Response :
1. Sample size calculation needs to be detailed for better understanding.
Response: We thank the reviewer for this suggestion. The sample size calculation has now been described in detail in the Methods section, including the software used (OpenEpi Version 3.01), the variables considered, and the reference study by Zhu et al. (2024), with the largest calculated sample size chosen for the study.
2. A flow chart could explain the total number of preterm newborns enrolled (population), cases (culture positive) and controls (culture negative).
Response: We appreciate this recommendation. A study flow diagram has now been added (Figure 1) to illustrate the total number of preterm neonates enrolled, exclusions, and the final allocation into cases (culture positive) and controls (culture negative). In addition, a textual description of the participant flow has been included in the Methods section for clarity.
3. Better to mention where and how investigations were done and who had followed up the babies.
Response: Blood cultures were performed using BACTEC system following NICU protocol. Samples were collected aseptically after 24 hours of life and processed according to standard microbiological procedures. Culture positivity defined sepsis cases. As this was a laboratory record–based observational study, no additional clinical follow-up of the neonates was performed; the study utilized only routinely collected laboratory data.
4. Data to be made available.
Response: We have included all the relevant data and the underlying findings under the Data Availability Section.
We sincerely thank the reviewer once again for their time and valuable suggestions. We believe that the revisions have strengthened the manuscript, and we hope that the changes adequately address all concerns and improve the clarity and overall quality of our study.