Joint effects of low grip strength and abdominal obesity on major cardiovascular events: an analysis of the prospective urban rural epidemiology (PURE)-China cohort study

Background Low muscle strength and abdominal obesity have been well established as independent risk factors for cardiovascular disease and mortality. These conditions often coexist and are biologically interrelated, with age-related declines in muscle function frequently accompanied by accumulation of abdominal fat, while excess abdominal adiposity may further exacerbate muscle catabolism through metabolic and inflammatory pathways. However, evidence regarding the joint associations of low muscle strength and abdominal obesity with cardiovascular risk remains limited, particularly in Asian populations. Purpose This study aimed to examine the joint associations low grip strength (GS) and abdominal obesity (AO) on major cardiovascular events and mortality. Methods We analysed data from participants aged 35–70 years in the PURE-China cohort study. GS was measured using a Jamar dynamometer, and low grip strength was defined based on sex- and age-specific distributions. AO was defined by waist circumference (≥90 cm in men and ≥85 cm in women). The primary outcome was major cardiovascular events. Associations were assessed using Cox frailty models, and interaction effects were evaluated on both multiplicative and additive scales, including the relative excess risk due to interaction (RERI) and the proportion attributable to interaction (AP). Sensitivity analyses were conducted using body mass index (BMI) to define overall obesity instead of abdominal obesity. Results Among 42,329 participants, 3,258 major cardiovascular events occurred during a median follow-up of 11.9 years. Evidence of interaction between low GS and AO was observed on both the multiplicative and additive scales (p for multiplicative interaction = 0.035; RERI 0.26, 95% CI 0.05–0.47; AP 0.18, 95% CI 0.04–0.31). Specifically, individuals with moderate/high GS and AO had an adjusted hazard ratio (HR) of 1.17 (95% CI 1.07–1.28), whereas those with low GS without AO had an adjusted HR of 1.06 (95% CI 0.96–1.18). The highest risk was observed among participants with both low GS and AO, with an adjusted HR of 1.49 (95% CI 1.30–1.70). No significant interaction was observed when overall obesity was used in sensitivity analyses. Conclusion In this large prospective Chinese cohort, low grip strength and abdominal obesity were jointly associated with the risk of major cardiovascular events, with marked differences across combinations of muscle strength and adiposity status. The coexistence of low grip strength and abdominal obesity was associated with the greatest cardiovascular risk, whereas either condition alone conferred more modest elevations in risk. The presence of interaction on both multiplicative and additive scales highlights the importance of considering abdominal adiposity in the context of muscle weakness when assessing cardiovascular risk.