Associations of Cumulative Conicity Index and Its Trajectories with Stroke Among Chinese Older Adults: A Prospective Cohort Study

Background: The conicity index (C-index) is an anthropometric indicator of body fat distribution. This study aimed to explore the associations of cumulative C-index and its trajectories with self-reported stroke among Chinese adults. Methods: Data were obtained from the China Health and Retirement Longitudinal Study. Exposures included cumulative C-index and C-index trajectories during 2011–2015. The outcome was self-reported incident stroke. Cumulative C-index was categorized by tertiles, and group-based trajectory modeling was used to identify distinct C-index trajectories. We used Cox proportional hazards regression models to investigate the associations of cumulative C-index and C-index trajectories with stroke. Results: A total of 6179 participants were included in this study. During a median follow-up of 4.6 years, incident stroke occurred in 489 (7.91%) participants. After adjusting for demographic characteristics and lifestyle-related factors, participants in the highest tertile of cumulative C-index (T3) had a 72% higher risk of stroke than those in the lowest tertile (T1) (HR = 1.72, 95% CI: 1.37–2.16, p < 0.001). Across C-index trajectory groups, individuals with a persistently high C-index had an 80% higher risk of stroke (HR = 1.80, 95% CI: 1.36–2.39, p < 0.001) than those with a persistently low C-index. After further adjustment for metabolic comorbidities and laboratory markers, the associations were somewhat attenuated but remained statistically significant. Conclusions: A higher cumulative C-index and persistently high C-index were associated with a significantly elevated risk of self-reported incident stroke among middle-aged and older Chinese adults.