[version 1; peer review: 1 approved with reservations]
No competing interests were disclosed.
Heart rate variability (HRV) is an important component of CAN and has been shown to be related to CAN. This study aims to evaluate cardiac autonomic neuropathy at different stages of CKD with the Bellavere score and to correlate CAN with lipids, plasma, electrolytes and blood pressure in patients with CKD at different stages.
All subjects will also be scored based on the Bellevere scoring system, the Valsava ratio, and the 30:15 ratio. Data will be analyzed using SPSS version 21 and appropriate statistical tests will be used depending on the study objectives and the data collected.
Structural or functional abnormalities of the kidneys present for more than three months is chronic kidney disease (CKD). Glomerular filtration rate (GFR) is generally considered the most common measure of kidney function. A GFR of less than 60 ml/min/1.73 m
2 indicates poor functioning of the kidneys; a GFR of less than 15 ml/min/1.73 m
2 indicates kidney failure. It can also be used to diagnose CKD. Proteinuria is another marker that can be used to diagnose CKD; of these, a urinary albumin excretion rate (AER) of more than 30 mg/24 hours and an albumin-creatinine ratio (ACR) of more than 30 is considered kidney disease. The prevalence of CKD in India has not been studied in longitudinal studies and only limited data are available from an Indian perspective.
Cardiac autonomic neuropathy (CAN) is an important indicator of cardiovascular mortality from arrhythmia. CAN is divided into three stages: deep breathing itself causes heart failure, the intermediate stage presents as a Valsalva reaction, and the severe stage presents as orthostatic hypotension.
Many articles have been published on cardiac autonomic neuropathy and its impact on conditions such as type 2 diabetes, adult epilepsy, fibromyalgia, hypertension, metabolic syndrome, and prediabetes, but none on CKD correlating CAN using the Bellavere score.
Animal models have shown that tolerance causes kidney damage. However, it is unclear how autonomic dysfunction predicts the development of CKD and ESRD in humans. Dysautonomia (sympathetic hyperactivity and/or parasympathetic depression) is a poorly studied renal injury. The results of several studies suggest that low self-efficacy may be an important risk factor for complications associated with ESRD and CKD, and these are the norm in these settings. Further research is needed on factors.
Although autonomic dysfunction has been reported to cause renal injury in animal models, it is unclear how autonomic dysfunction predicts the development of CKD and ESRD in humans.
Findings from several completed studies suggest that occupational inactivity may be an important risk factor for ESRD and CKD-related hospitalizations and encourage further research to identify mechanisms in these institutions.
Some small studies show that people with CKD show lower HRV than healthy people. Although nephrosclerosis, which can lead to recurrent autonomic imbalances, may be the main cause of this link, it is not clear which autonomic imbalance existed before and could lead to the development of CKD.
A cross-sectional study found that young adults with poor cardiovascular health were more likely to develop kidney disease. This group was followed longitudinally to elucidate the association between autonomic and renal failure and the impact of interventions in this population.
In addition, the review described the effect and relationship between impaired kidney function, modification, and replacement.
This study will be conducted in a group of CKD patients who will be followed up to identify risk factors for the development of CKD in the future.
Evaluation of cardiac autonomic neuropathy via Bellavere’s score in various stages of chronic kidney disease To correlate cardiac autonomic neuropathy with lipid profiles like cholesterol, triglycerides, low density lipoprotein (LDL) and anemia, electrolytes, and blood pressure in all stages of CKD. To compare CAN in patients of CKD with or without hemodialysis
All patients who meet the diagnosis of CKD at Acharya Vinoba Bhave Rural Hospital (AVBRH), DMIHER (Datta Meghe Institute of Higher Education and Research) according to the Modification of Diet in Renal Disease (MDRD) criteria will be included in this study.
All patients meeting the inclusion and exclusion criteria will be included in this study after written informed consent has been obtained.
The information collected will be kept confidential. The data will be encoded and entered as a password-protected code. The patient’s name and other personal information will not be disclosed.
Patients who met CKD criteria and had informed consent, according to the National Kidney Foundation, were included. Patients who did not give consent had other conditions, refused the study, lost follow-up, died, and had missing data were excluded from the study.
This protocol has been approved by Institutional Ethical Committee of Datta Meghe Institute of Higher Education and Research on 27th June, 2022 (approval no. IEC20221088). Confidentiality will be ensured for all participants. Prior to taking part in the process, participant’s written consent will be obtained and they will be informed that they have the option to revoke their consent at any moment.
Patients satisfying the criteria of CKD according to the national kidney foundation Patients giving consent
Patients not consenting Patients with other comorbidities Patients refusing investigations Loss to follow-up, death and incomplete information Patients who are seriously ill
Bellavere’s scoring system, classification according to the total score of CAN and stages of CKD have been explained via
(BP- Blood Pressure, VR- Valsalva Ratio).
| COMPONENTS | SCORE | ||
|---|---|---|---|
| 0 (Normal) | 1 (Borderline) | 2 (Abnormal) | |
| Heart rate variability | >15 | 10–15 | <10 |
| VR | ≥1.21 | 1.11–1.20 | ≤1.10 |
| 30:15 ratio | ≥1.04 | 1.01–1.03 | ≤1.0 |
| BP-standing | ≥10 | 11–29 | ≥30 |
| BP-hand grip | ≥16 | 11–15 | ≤10 |
| Score | Interpretation |
|---|---|
| 0–1 | No neuropathy |
| 2–4 | Autonomic neuropathy |
| 5–10 | Severe autonomic neuropathy |
| Stages | Groups | e GFR by MDRD |
|---|---|---|
| Stage 1 | GFR >90 | 111±26.2 |
| Stage 2 | GFR 60–90 | 77±23.8 |
| Stage 3 | GFR 30–59 | 39±9 |
| Stage 4 | GFR 15–29 | 21±6 |
| Stage 5 | GFR<15 | 13±4.5 |
The skin over the median nerve of the cubital fossa will be disinfected with alcohol. A tourniquet will be used proximal to the fossa. The blood will be removed from the vein using a sterile standard venipuncture needle.
Systolic blood pressure response to standing: systolic blood pressure will first be measured in a supine position and then the patient will be asked to stand and systolic blood pressure will be measured again 2 minutes later.
The normal response is <10 mmHg decrease with an initial drop of 10–29 mmHg is considered borderline normal; abnormal is a drop of >30 mmHg with symptoms as shown in
Diastolic blood pressure response to isometric exercise: The subject squeezes a handgrip dynamometer to establish a maximum reading. Grip is then squeezed at 30% maximum for 5 min. A normal response for diastolic blood pressure is a rise of > 16 mmHg in the opposite arm.
In this test, subjects are asked to take deep breaths six times per minute, inhale for five seconds per minute, and exhale for five seconds. The ECG will be recorded during a deep breath with a marker indicating the beginning of each inhalation and exhalation. The maximum and minimum R-R intervals in each respiratory cycle will be measured using a caliper and converted to beats per minute.
Values equal to or less than 10 beats per minute are considered abnormal readings. A heart rate higher than 15 beats per minute is considered normal; however, anything below 10 bpm is abnormal.
The ratio of the maximum R-R interval to the minimum R-R interval on the EKG is called the Valsalva ratio. In order to calculate this ratio, the subject is asked to breathe for 15 seconds into the mouth connected to the manometer while the mercury manometer is held at 40 mmHg pressure. The ECG will be recorded during and 45 seconds after this manoeuvre. The maximum and minimum R-R intervals will be recorded to calculate the Valsalva ratio. The ratio is less than or equal to 1.
The longest R-R interval (measured at 30 beats) and the shortest R-R interval (measured at 15 beats) will be measured after 45 seconds of standing. The ratio of these two measurements is called the 30:15 ratio. A ratio less than or equal to 1 is considered abnormal.
Z - Probability of type 1 error at 95% confidence interval (constant Value- 1.96)
P - Incidence of Cardiac autonomic neuropathy in CKD stage V (in this case 0.7242)
d - Precession level/Margin of error (constant value- 0.09)
On substituting these values in the formula, N = 95.
Therefore, the calculated sample size for this study is 95 at a 95% confidence interval and 5% probability of alpha error.
Complete blood count, serum albumin, kidney function test, BMI, waist circumference, blood pressure, fasting lipid profile, 2D echocardiography, electrocardiography.
This study intends to study the relationship between CKD and CAN based on variables like blood pressure, anaemia, electrolytes and lipid profile (cholesterol, triglycerides, LDL) in patients with CKD. Based on the literature review, it is anticipated that the results of this study will reveal a positive association between chronic kidney disease and cardiac autonomic neuropathy at all stages of CKD. The study is also expected to show higher Bellavere scoring in CKD patients at different stages. Finally, in the comparative analysis, the outcome of this study is expected to show that CAN is higher or more severe in CKD patients on hemodialysis as compared to CKD patients not on hemodialysis.
This study will be published in an indexed journal.
Data collection has not yet started.
CKD is characterized by the presence or absence of kidney function for more than three months, regardless of the cause. CAN can damage weak blood vessels that supply the heart and blood vessels, leading to abnormalities in heart rate control and vascular dynamics. Few studies investigating the relationship between CKD and CAN have shown a strong association between the two conditions and a weak cardiac neuropathy observed in patients with different stages of CKD compared with those without CKD.
Thapa L
This study also found a positive correlation between the severity of autonomic dysfunction and the severity of CKD.
Malik S.
Oliveira CA de
This prospective cross-sectional study aims at estimating the impact of CAN in different stages of CKD. Cardiovascular causes are a major contributor to mortality in CKD patients and hence a study correlating them is necessary. The Bellavere score for CAN in relation to CKD has not yet been published, and there are no such publications available in India.
This study aims to evaluate CAN in CKD patients via Bellavere’s scoring system and hence calculate the severity of CAN in different stages of chronic kidney disease. CAN is an established indicator of cardiovascular neuropathy and hence this study would help in establishing whether early diagnosis of CAN in CKD patients would help decrease cardiovascular morbidity and mortality in CKD patients.
No underlying data associated with this protocol.
The corresponding author will be conducting the complete study as his thesis for his post-graduation in General Medicine. All authors have equally contributed to the conception, design and analysis of this protocol.
All authors confirm that they have read and agree to the contents of this manuscript. Also, the easily reproducible materials described in the manuscript are freely available to any researcher who wishes to use them for non-commercial purposes.
The rationale for the study is clearly articulated, with an appropriate and logical link between chronic kidney disease (CKD) and cardiac autonomic neuropathy (CAN). The background section provides a concise overview of the pathophysiological mechanisms underlying autonomic dysfunction in CKD and highlights the gap in existing literature, particularly the lack of Indian data correlating CAN with CKD using the Bellavere scoring system. The study objectives are well-defined, specific, and aligned with the stated rationale. They appropriately focus on evaluating CAN using Bellavere’s score across different stages of CKD, correlating it with metabolic and hemodynamic variables, and comparing CAN severity between patients on hemodialysis and those not undergoing dialysis. However, the protocol could be strengthened by explicitly stating the central hypothesis, outlining the expected direction of associations (e.g., higher Bellavere scores with increasing CKD severity), to provide a clearer research focus.
The chosen study design—a prospective cross-sectional approach—is suitable for addressing the research question, which seeks to identify associations between CAN severity and CKD progression rather than causal relationships. The design appropriately allows for correlation analysis and comparative evaluation across CKD stages and dialysis status. The inclusion of 95 participants, supported by a transparent and statistically justified sample size calculation, lends methodological rigor. The use of the Bellavere scoring system, incorporating standardized autonomic function tests such as heart rate variability, Valsalva ratio, and 30:15 ratio, ensures objective and quantifiable assessment. Acknowledging that causal inference cannot be drawn from a cross-sectional design, the study nonetheless appropriately meets its descriptive and correlational objectives.
The methodology section provides comprehensive procedural detail, enabling replication by other investigators. Inclusion and exclusion criteria, ethical approval, and informed consent processes are well-described. The procedures for physiological testing—including heart rate variability, Valsalva ratio, 30:15 ratio, and blood pressure responses—are explicitly outlined, with well-defined normal and abnormal thresholds consistent with the Bellavere scoring system. Tables summarizing these cut-off values, CKD staging, and scoring interpretation enhance clarity. The description of blood collection, biochemical analyses, and data confidentiality measures are appropriate. However, additional detail regarding the specific statistical tests to be employed (e.g., correlation, regression, or ANOVA) and the methods for adjusting for potential confounders such as age, diabetes, hypertension, and medication use would further strengthen methodological transparency.
As the study is still in the preparatory phase and data collection has not yet commenced, datasets are not available for review. Nevertheless, the planned data structure is logical and well-supported by the provided tables, which clearly outline the scoring framework and CKD classification criteria. The inclusion of a data coding and password protection plan indicates attention to data management and confidentiality. To enhance future usability and reproducibility, the protocol would benefit from specifying the data management strategy in greater detail, including data entry format, variable definitions, data validation procedures, and plans for data sharing or availability upon reasonable request after study completion.
The protocol clearly defines the Bellavere scoring system and each of its components; however, it currently lacks specification of the qualifications and standardization requirements for assessors performing the autonomic function tests. For consistency, validity, and reduction of inter-observer variability, the study should explicitly state that all assessments will be conducted by trained and certified assessors—preferably physicians or clinical physiology technicians with prior experience in autonomic testing—who have undergone standardized training and competency evaluation based on a study-specific Standard Operating Procedure (SOP). The SOP should detail patient preparation, equipment calibration, environmental conditions, scripted instructions, and scoring criteria. Documentation of inter-rater reliability (e.g., using kappa or intraclass correlation coefficients) should be planned to ensure ongoing quality assurance. Incorporating these standardization measures will ensure uniform assessment across all participants and significantly enhance the reliability and reproducibility of the study findings.
Is the study design appropriate for the research question?
Yes
Is the rationale for, and objectives of, the study clearly described?
Yes
Are sufficient details of the methods provided to allow replication by others?
Partly
Are the datasets clearly presented in a useable and accessible format?
Not applicable
Reviewer Expertise:
Pediatric nephrologist, research methodologist.
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.