Modification of the association between obesity phenotypes and cardiovascular disease by social determinants of health: A prospective cohort study

Abstract Aims The relationship between obesity phenotypes and cardiovascular disease (CVD) risk may be influenced by social determinants of health (SDOH), but evidence remains limited. Materials and Methods This cohort study included 89 237 Chinese adults (mean age: 53.9 years; 39.0% male) free of CVD at baseline from the China PEACE Million Persons Project. Obesity phenotypes were defined by BMI and metabolic status. A composite SDOH index was used to classify participants into high and low burden groups. Cox proportional hazards models assessed the associations of obesity phenotypes with incident CVD, incorporating interaction terms to examine effect modification by SDOH. Results Over a median follow‐up of 3.47 years (IQR: 2.57–4.28), 4999 incident CVD events (5.6%) were recorded. Compared with metabolically healthy normal weight individuals, metabolically unhealthy obese participants exhibited the highest CVD risk (HR: 1.75; 95% CI: 1.61–1.89). These associations were modified by SDOH burden, with stronger relative risks in the low SDOH burden group (P interaction = 0.005). Joint analyses revealed that high SDOH burden further increased CVD risk across most phenotypes. The modifying effect of SDOH was more evident in older adults. Sensitivity analyses confirmed results robustness. Conclusion Obesity phenotypes were differentially associated with CVD risk, and these associations were shaped by social context. Individuals with lower SDOH burden may be more vulnerable to metabolic dysfunction. These findings highlight the need for prevention strategies that integrate both biological and social risk to improve CVD risk stratification. Lay Summary This study followed nearly 90 000 adults in China to understand how obesity phenotypes and social determinants of health (SDOH)—such as education, income, and access to resources—interact to influence cardiovascular disease (CVD). Beyond confirming that metabolically unhealthy phenotypes carry greater CVD risk, the study demonstrated that these associations vary by SDOH burden, with stronger relative risks in favourable social conditions. Poor social conditions increased CVD risk across most obesity phenotypes, particularly among older adults.