Diagnostic value of urea, creatinine and blood parameters in patients with pneumonia diagnosed with chronic obstructive

This study aimed to investigate the diagnostic value of urea, Background: creatinine and other blood parameters in patients with pneumonia diagnosed with chronic obstructive pulmonary disease (COPD) for the first time. In this retrospective study, patients who had been diagnosed Methods: with COPD for the first time and were diagnosed with pneumonia were included. A total of 193 patients were divided into three groups as COPD + pneumonia (n=123), COPD (n=36) and pneumonia (n=34). In total, 59 women (48.0%) and 64 men (52.0%) from the COPD + Results: pneumonia group, 13 women (36.1%) and 23 men (63.9%) from the COPD group, 21 women (61.8%) and 13 men (38.2%) from the pneumonia group were assessed. The mean age of the COPD + pneumonia group was 69.58±13.62, 66.28±12.55 for the COPD group and 53.97±19.72 for the pneumonia group. The highest values of C-reactive protein (CRP), urea, creatinine, white blood cells (WBC), neutrophils, eosinophils and hemoglobin were the highest in COPD + pneumonia group. CRP levels were significantly different between COPD + pneumonia group (p<0.05). The parameters urea, WBC and neutrophils were significantly different between COPD + pneumonia group and pneumonia group (p<0.05). There was a statistically significant difference between COPD and pneumonia groups in terms of neutrophils and eosinophils values (p<0.05). According to the results of receiver operating characteristic analysis, the diagnostic value of the urea parameter in determining the COPD + pneumonia group was not statistically significant (p>0.05). On the other hand, the diagnostic value of CRP, WBC and neutrophils values were statistically significant (p<0.05). Elevation in WBC and neutrophil values in patients Conclusions: diagnosed with pneumonia have an important role in diagnosis of COPD.


Introduction
Pneumonia has been known since late 1800s, and has been recognized as a major cause of death 1 .Pneumonia is one of the most common causes of mortality in children under 5 years, and common in South Asia and sub-Saharan Africa; it is a form of acute respiratory tract infection 2 .The annual incidence of community-acquired pneumonia (CAP) ranges from 5 to 11 per 1000 persons in the United States.It is common in the winter.There are several risk factors associated with CAP, such as neurologic and gastrointestinal abnormalities, male gender, multilobar involvement, high fever, etc. 3 .CAP is an infection of the pulmonary parenchyma by causative microorganisms 4 .Streptococcus pneumonia is the leading cause of bacterial pneumonia, causing 30-50% of childhood pneumonia in developing countries 5 .In diagnosis of the disease, chest X-rays, complete blood count and electrolyte count tests are used 5 .In treatment of pneumonia, medication and antibiotic therapy are commonly used.A 6-month observation is recommended by the UK National Institute for Health and Care Excellence.In addition, it is important to examine environmental conditions as well as given medication or therapy 6 .It is reported that smoking, chronic lung diseases, heart disease and diabetes increase the prevalence of disease 7 .
Chronic obstructive pulmonary disease (COPD) is another common lung disease, characterized by a slow and debilitating progression 8 .It causes changes in the lungs with airflow restrictions and physical symptoms such as dyspnoea 9 .Obstructive bronchiolitis and emphysema may represent comorbidities of COPD 10,11 .There is evidence that inhaled corticosteroids, a treatment for COPD, and increase risk of pneumonia 12 .In addition, previous research has shown that exacerbation of COPD and pneumonia in COPD has different clinical and analytical properties, although mechanisms are similar 12,13 .
This study aimed to investigate the diagnostic value of urea, creatinine and some blood parameters in patients with pneumonia that had been diagnosed with COPD for the first time.

Study participants and eligibility
In this retrospective study, patients who had been diagnosed with COPD for the first time and were diagnosed with Pneumonia and who were admitted to Kadıköy Medicana Hospital, Istanbul, Turkey, between 12 October 2017 and 12 October 2018 were included in the study.A sample of convenience was used, with a voluntary patient consent form.The eligibility criteria were as follows: -Previously diagnosed with pneumonia, -First diagnosed with COPD, -Without a history of clinical intervention in patient epicrisis, -Without a malignant disorder -Completed patient consent form A total of 123 patients with pneumonia among 160 patients who met inclusion criteria were included in the study.A total of 193 patients were divided into three groups as COPD + pneumonia (n = 123), COPD (n = 36) and pneumonia (n = 34).In the second group of patients diagnosed with COPD, the patients who were not diagnosed with pneumonia were designated as the first control group, and patients diagnosed with pneumonia and patients who were not diagnosed with COPD was the second control group.Each patient provided written informed consent for their clinical details to be used when admitted; the hospital management granted approval for this study.

Variables assessed in this study
The variables assessed in this study were age, gender, CRP, Urea, Creatine, WBC, NEU, EOS and HGB, which were taken from patient records with approval.

Statistical analysis
The binary and ordinal data were described by frequency analysis and the other measurement parameters by mean and standard deviation values.Kolmogorov-Smirnov analysis was performed to assess normality distribution of the data before the difference analysis.Independent samples t-test was used for the difference of normal distribution between WBC and hemoglobin data.The Mann-Whitney U-test was used to analyze the difference between paired groups (COPD + pneumonia vs COPD only; COPD + pneumonia vs pneumonia only; COPD only vs pneumonia only) of CRP, urea, creatinine, neutrophils and eosinophils parameters which did not conform to normal distribution.Receiver operating characteristics (ROC) analysis was used for CRP, urea, WBC and NEU.All analyses were performed in SPSS 17.0 for Windows, and performed at 95% confidence interval.

Demographic information and clinical values
The distribution of gender, age and some clinical parameters of the case groups included in the study are shown in Table 1.
In total, there were 59 women (48.0%) and 64 men (52.0%) in the COPD + pneumonia group, 13 women (36.1%) and 23 men (63.9%) in the COPD group, and 21 women (61.8%) and 13 men (38.2%) in the pneumonia group included in the study.The mean age of patients was 70±14 in the COPD + pneumonia group, 66±13 in the COPD group and 54±20 in the pneumonia group.The highest values of CRP, urea, creatinine, WBC, neutrophils, eosinophils and hemoglobin were observed in the COPD + pneumonia group.The results of the differential analysis of the clinical parameters in the study are presented in Table 2. Raw values are available on Open Science Framework 14 .

Data analysis
According to the results of the difference analysis, there was a statistically significant difference between CRP levels of the COPD + pneumonia and COPD groups (p<0.05).The parameters urea, WBC and neutrophils were significantly different between the COPD + pneumonia and pneumonia groups (p<0.05).There was a statistically significant difference between COPD and pneumonia groups in terms of neutrophils and eosinophils values (p<0.05).The results of ROC analysis of CRP, urea, WBC and neutrophils variables were given as follows.
According to the results of the ROC analysis (Figure 1), the diagnostic value of the urea parameter in determining the COPD + pneumonia group was not statistically significant (p>0.05).
On the other hand, the diagnostic value of CRP, WBC and neutrophils values were statistically significant (p<0.05).The distribution of areas under the curve according to ROC analysis is given in Table 3.
The area under the curve was the highest for the CRP value.

Discussion
Pneumonia [15][16][17] and COPD [18][19][20] are two diseases that are the focus of considerable research into respiratory complaints.In addition, there are studies reporting the distribution of these diseases in different demographic groups [21][22][23][24][25][26] .In our study, pneumonia was more common in women, whereas COPD was more common in men.In both groups, the gender distributions were similar, although males made up the majority.However, the mean age of patients was the highest in COPD + pneumonia patients.
In patients with COPD and pneumonia, the clinical condition of the patients is poorer than for patients with one or the other conditions, and it is suggested that two diseases trigger each other [25][26][27][28][29][30][31][32][33][34] .In our study, urea and creatinine levels were higher in patients with pneumonia who were diagnosed with COPD for the first time.WBC and neutrophil values were statistically higher among patients with COPD than in patients with only pneumonia.The difference in urea, WBC and neutrophil values was not significant between the COPD and COPD + pneumonia groups.It can be said that the increase in these three parameters may have diagnostic implications for COPD in patients with pneumonia.

Conclusion
According to the results of this study, a history of pneumonia aggravates the clinical course of patients with COPD for the first time.On the other hand, the increase in CRP, WBC and neutrophil values in patients diagnosed with pneumonia but not COPD may give the first indication of a possible development of COPD.
According to the results of ROC analysis, CRP is among the most important determinants of patients with the first time diagnosed with COPD and diagnosed with pneumonia.On the other hand, WBC and neutrophil elevation in patients with previously diagnosed pneumonia may also be an important factor in the diagnosis of COPD.The benefits of publishing with F1000Research: Your article is published within days, with no editorial bias You can publish traditional articles, null/negative results, case reports, data notes and more The peer review process is transparent and collaborative Your article is indexed in PubMed after passing peer review Dedicated customer support at every stage For pre-submission enquiries, contact research@f1000.com

Table 3 . Receiver operating characteristic analysis results and areas under curves. Test result variable Area Standard error p-value Asymptotic 95% confidence interval Lower bound Upper bound
CRP, C-reactive protein; WBC, white blood cells; NEU, neutrophil.