The serum creatinine to cystatin C ratio predicts the risk of acute exacerbation of chronic obstructive pulmonary disease

Background: The aims of acute exacerbation of chronic obstructive pulmonary disease (AECOPD) treatment are to minimize the negative impact of the current exacerbation and to prevent the development of subsequent events. Hence, it is important to identify serological indicators that are readily available at the time of hospital admission to assess the prognosis of patients with AECOPD. Methods: : All patients hospitalized in a Department of Respiratory and Critical Care Medicine of tertiary care hospital between January 2021 and December 2021 for AECOPD were analyzed using univariable correlations and binary logistic regression analysis with two models for associations between demographic, clinical and laboratory features and AECOPD risk. Results: : The Cre/Cys C ratio was significantly associated with age (r = –0.206, P = 0.000), weight (r = 0.331, P = 0.000), BMI (r = 0.133, P = 0.007), and FVC% predicted (r = 0.130, P = 0.009). Multiple regression was run to predict the Cre/Cys C ratio from age, weight, BMI, FEV1/FVC ratio and FVC% predicted FABP-4, with F (5, 405) = 24.571, P=0.000, R2 = 0.233. The results showed that the most significant predictors of the Cre/Cys C ratio were age (P=0.007), weight (P=0.000), BMI (P=0.000), and predicted FEV1 (P=0.000). Multivariate analysis was performed to determine whether the Cre/Cys C ratio was a predictor of AECOPD risk. Model 1 showed that a low Cre/Cys C ratio was associated with an increased hospital LOS (odds ratio (OR): -0.114, 95% confidence interval (CI): -0.061- -0.005) and admission to the ICU (OR: 0.951, 95% CI: 0.907-0.996). After adjustment for potential confounding factors, model 2 showed that a low Cre/Cys C ratio was not independently associated with AECOPD risk. Conclusion: The present study indicated that the Cre/Cys C ratio is an easy, cheap, repeatable and promising tool that allows us to evaluate the risk of AECOPD using serum markers. A low Cre/Cys C ratio was associated with a prolonged LOS and admission to the ICU in AECOPD patients. However, the associations were not independent.