Dose–response relationship between Frailty Index and Stroke among middle-aged and elderly Chinese

Abstract Background Stroke has emerged as the leading cause of mortality in China, with the burden of the disease increasing with the aging population. Recent research has established a correlation between frailty and stroke, with the frailty index serving as a comprehensive measure of frailty in elderly populations. This study aimed to explore the dose-response relationship between frailty index and stroke, with the objective of providing a reference for effective stroke identification in middle-aged and elderly individuals, thereby preventing the onset of the disease. Methods The data used in this study were derived from the China Health and Retirement Longitudinal Study (CHARLS) database from 2011 to 2018. Proportional hazards model was utilized to investigate the impact of frailty index on stroke risk, while restricted cubic spline analysis was employed to examine the dose-response relationship between frailty index and stroke. Subgroup analysis was used to further understand whether the frailty index has an effect on the occurrence of stroke in different subgroups. Results A total of 11328 participants were included in the study, with 401 (3.3%) stroke patients. Frailty and pre-frailty were associated with a high risk of stroke events compared with robust group (HR, 3 . 89, 95%CI, 2 . 88-5 . 26 ), ( HR, 2 . 09, 95%CI, 1 . 60-2 . 75 ), after adjusting for all covariates. There was a non-linear relationship between frailty index and stroke in the restricted cubic spline regression model. Frailty index was a risk factor of stroke when it exceeded 0.13. Taking the robust as reference, subgroup analysis results showed a significant interaction with the frailty index in all subgroup analyses except for the smoking group. Conclusion Pre-frailty and frailty were significantly associated with stroke risk. Frailty index had a nonlinear relationship with stroke occurrence, and frailty index >0.13 was significantly correlated with stroke occurrence. Frailty index is an independent predictor of stroke occurrence.