Associations of metabolic score for insulin resistance and new-onset stroke in middle-aged and older adults: a national cohort study.

Abstract

Background: Metabolic score for insulin resistance (METS-IR) is acknowledged as a reliable indicator of insulin resistance and cardiometabolic risk. This study aims to explore the relationship between cumulative METS-IR (cumMETS-IR) and METS-IR change patterns with new-onset stroke.

Methods: 4344 participants from the China Health and Retirement Longitudinal Study (CHARLS) with follow-up until 2020 were utilized in this study. cumMETS-IR was calculated as the area under the curve of METS-IR values from 2011 to 2015. K-means clustering analysis was employed to discern distinct METS-IR change patterns over this interval. Associations of cumMETS-IR and METS-IR change patterns with incident stroke were examined using Cox proportional hazards models and restricted cubic splines (RCS). Mediation analysis assessed whether diastolic blood pressure (DBP) accounted for the association between cumMETS-IR and incident stroke.

Results: There were 385 (8.86%) new stroke events over 5-years median follow-up. RCS analysis showed that cumMETS-IR was positively correlated with incident stroke (P-overall = 0.013, P-nonlinear = 0.252). Compared with the lowest quartile, the highest quartile was associated with a higher incidence of stroke (adjusted hazard ratio [HR] 1.72, 95% confidence interval [CI] 1.22-2.42, P = 0.002). Four distinct METS-IR change patterns were identified using k-means clustering: low-stable (30.5%), low-to-moderate stable (35.9%), moderate-to-high stable (24.7%), and high-decreasing (8.9%). Participants following the high-decreasing pattern was associated with the highest incidence of stroke compared to those in the low-stable patterns (adjusted HR 1.61, 95% CI 1.08-2.42, P = 0.021). The core findings remained robust across a series of sensitivity analyses. Mediation analysis revealed that DBP partially explained this association, with a mediation proportion of 9.6%.

Conclusion: Both cumMETS-IR and METS-IR change were associated with increased incidence of stroke in middle-aged and older Chinese adults. Monitoring changes in METS-IR over time may help characterize metabolic status more comprehensively and offer supportive information for stroke-related health assessment.