Relationship between obesity severity, metabolic status and cardiovascular disease in obese adults

BACKGROUND: Evidence about the associations between obesity severity, metabolic status and risk of incident cardiovascular disease (CVD) in adults with obesity remains limited. METHODS: The study included 109,301 adults with obesity free of prior CVD based on the UK Biobank cohort. Metabolic status was categorized into metabolically healthy obesity (MHO; free of hypertension, hypercholesterolemia and diabetes) and metabolically unhealthy obesity (MUO). Obesity severity was classified into three levels: class I (body mass index of 30.0-34.9 kg/m² ), II (35.0-39.9) and III (≥40.0). Cox proportional hazards models were used for analyses. RESULTS: There were 8059 incident CVD events during a median follow-up of 8.1 years. MUO was significantly associated with a 74% increased CVD risk compared with MHO (HR = 1.74, 95% CI: 1.62-1.83). There was a significant interaction between obesity severity and metabolic status on an additive scale regarding CVD risk. When taking class I obesity as reference, class II was nonsignificantly associated with an increased risk of CVD in the MHO group (HR = 1.07, 95% CI: 0.90-1.27), while class III was significantly related to increased risks of CVD (HR = 1.48, 95% CI: 1.12-1.96). In the MUO group, both classes II and III were significantly related to increased risks of CVD. Significant subgroup effects of age (p = .009) and sex (p = .047) were observed among participants with MUO but not in the MHO group. CONCLUSIONS: Both elevated obesity severity and MUO were significantly associated with increased risks of CVD in adults with obesity, while metabolic status could modify the relationship between obesity severity and CVD risk. More research is needed to further clarify the relationship.