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.

引言：红细胞分布宽度与血小板比值（Red blood cell distribution width-to-platelet ratio，RPR）作为一种新型炎症指标，已被证实可作为部分其他疾病的预后因子，但目前针对重症急性缺血性脑卒中（acute ischemic stroke，AIS）患者的预后评估价值却鲜有研究。本研究旨在探讨RPR与该类患者院内全因死亡率的关联。方法：本研究从重症医学信息数据库IV1.0（Medical Information Mart for Intensive Care IV1.0）中提取临床数据。本研究的主要结局为重症急性缺血性脑卒中患者的院内全因死亡率，核心自变量为RPR。为探讨重症AIS患者RPR与院内全因死亡率的关联，本研究采用多变量logistic回归分析、平滑曲线拟合及分层分析开展研究。结果：本研究共纳入2673例入住重症监护病房的急性缺血性脑卒中患者。多变量分析结果显示，院内死亡率与RPR呈正相关（比值比（odds ratio，OR）=1.28，95%置信区间（confidence interval，CI）：1.02~1.59）。通过两段式logistic回归模型分析发现，RPR的拐点为1.89%。在拐点左侧（RPR≤1.89%），未检测到RPR与院内全因死亡率存在显著关联（OR(95%CI)：0.73(0.41,1.31)，P=0.2884）；与之相反，在拐点右侧（RPR>1.89%），RPR与院内全因死亡率呈显著正相关（OR(95%CI)：1.61(1.18,2.19)，P=0.0027）。结论：RPR与重症急性缺血性脑卒中患者的院内全因死亡率呈非线性关联。