Comparative analysis of C-Reactive protein levels among Non-comorbid, Comorbid, and Multimorbid Hospitalized COVID-19...

C-reactive protein (CRP) is one of the most commonly monitored inflammatory markers in patients with COVID-19 to gain insight into the inflammation level in the body and to adopt effective disease management and therapeutic strategies. COVID-19 is now less prevalent, and the study of CRP as a biomarker of inflammation still needs deeper understanding, particularly in understanding its role among patients with comorbidities, which are known to influence inflammatory responses and increase the risk of severe outcomes during acute and chronic infectious diseases. The objective of this study was to evaluate the association of major comorbidities such as ischemic heart diseases, diabetes, chronic kidney disease, hypertension, and lung infections e.g. tuberculosis with serum CRP levels in hospitalized COVID-19 patients.

This study involves a retrospective observational framework to monitor CRP levels among hospitalized COVID-19 patients after getting ethical approval and patient consent. The information on underlying health conditions or comorbidities and age was collected from the patient data files. The requirement of ventilation, ICU admission, mortality & survival, and CRP levels were monitored based on their daily updates in the data file. Furthermore, the association of CRP levels was evaluated with disease severity and mortality.

In this study 618 out of 750 hospitalized COVID-19 patients, of which 62.6% were male and 37.4% were female, the levels of serum CRP were significantly influenced by age and comorbidities. No case of hospitalization was observed in children (≤ 14 years) during the study period, while 38.3% of patients belonged to the old age group (≥ 65 years). Comorbidity status varied, with 36.1% of patients without having any comorbidities, 27.8% with one, 23.6% with two, and 12.5% with three or more comorbidities. Descriptive statistics revealed that the CRP levels in the study population averaged 88.92 mg/L (SD = 63.95), ranging from < 1 mg/L to 900 mg/L, with significant variations observed across different comorbidities and age groups. CRP levels, analyzed by the Kruskal-Wallis test, showed significant variations in different age groups of COVID-19 patients (χ² = 66.741, df = 3, p < 0.001). Moreover, pairwise comparisons showed considerable differences between young and middle-aged groups (Z = -2.724, p < 0.01) and young and old age groups of COVID-19 patients (Z = -3.970, p < 0.001). The most prevalent comorbidities observed in COVID-19 patients in this study were hypertension (42.1%), diabetes (33.8%), ischemic heart disease (16.5%), asthma (11.2%), chronic kidney disease (7.9%) and Tuberculosis (1.9%). The CRP levels fluctuate and also significantly differ among different comorbidities. COVID-19 patients with diabetes were observed to have higher CRP levels than non-diabetics (mean CRP: 126.96 mg/L vs. 88.92 mg/L, Z = -5.724, p < 0.001), and those with hypertension also encountered elevated CRP (mean CRP: 355.37 vs. 276.19 mg/L, Z = -5.447, p < 0.001). Similar tendencies were detected in COVID-19 patients with ischemic heart disease (mean CRP: 385.43 mg/L, Z = -4.704, p < 0.001), chronic kidney disease (mean CRP: 412.37 mg/L, Z = -4.206, p < 0.001) as well as with tuberculosis (mean CRP: 458.08 mg/L, Z = -2.914, p < 0.01). CRP levels on days 1 and 3 of hospitalization showed a decline (88.92 mg/L to 67.89 mg/L), representative of a response to treatment to reduce the inflammation in the body. Furthermore, high levels of CRP were significantly associated with a high requirement of non-invasive ventilation (mean CRP: 110.80 mg/L vs. 76.82 mg/L, p < 0.05), mechanical ventilation (mean CRP: 134.46 mg/L vs. 77.25 mg/L, p < 0.05) and ICU admission (mean CRP: 126.96 mg/L vs. 72.79 mg/L, p < 0.05). The Cox regression analysis showed that there is a considerable association of CRP level with the expected length of hospitalization, each 1-unit increase in CRP levels was associated with a 0.6% increase in extended stay risk (hazard ratio = 1.006, 95% CI: 1.004-1.008, p < 0.001). Furthermore, the logistic regression analysis performed on CRP levels that was monitored on the first day of hospitalization, revealed that there was a 2.7% increase in mortality odds with each unit increase in CRP (odds ratio = 1.027, 95% CI: 1.022-1.033, p < 0.001), which suggest CRP as a potential mortality predictor.

Elevated CRP levels in COVID-19 patients with comorbidities like diabetes, hypertension, ischemic heart disease, and chronic kidney disease were strongly associated with increased disease severity, including higher ventilation requirements and mortality. Patients with these comorbidities showed significantly higher CRP levels, which correlated with worse outcomes, including ICU admissions and prolonged hospital stays, emphasizing the importance of CRP as a predictor for severe complications in patients with infectious diseases along with one or more comorbidities.