Supplementary Material for: Red Cell Distribution Width to Platelet Count Ratio: A promising predictor of in-hospital all-cause mortality in critically ill patients with acute ischemic stroke

Introduction: Red blood cell distribution width-to-platelet ratio (RPR), a novel inflammatory index, has already been proven as a prognostic factor in some other diseases, but its prognostic effect on critically ill patients with acute ischemic stroke (AIS) has rarely investigated. This study aimed to investigate the association between RPR and in-hospital mortality in these patients. Methods: We extracted clinical data from the Medical Information Mart for Intensive Care IV1.0 database. The primary outcome was in-hospital all-cause mortality of patients with critical AIS. The main independent variable was RPR. To investigate the association between RPR and in-hospital all-cause mortality in patients with critical AIS, multivariable logistic analyses, smooth curve fitting, and stratified analyses were conducted. Results: In total, 2,673 patients with AIS who were admitted to the intensive care unit were included in the study. In the multivariable analysis, in-hospital mortality was positively related to RPR (odds ratio (OR) 1.28, 95% confidence interval (CI) 1.02–1.59). According to the two-piecewise logistic regression model, we found that the inflection point of RPR was 1.89%. To the left of the inflection point (RPR ≤1.89%), we did not detect any relationship between RPR and in-hospital all-cause mortality (OR (95% CI): 0.73 (0.41, 1.31), P = 0.2884). In contrast, to the right of the inflection point (RPR > 1.89%), RPR was positively related to in-hospital all-cause mortality (OR (95% CI): 1.61 (1.18, 2.19), P = 0.0027). Conclusions: RPR showed a nonlinear relationship with in-hospital all-cause mortality in patients with critical AIS.