The impact of metabolic heterogeneity of obesity and transitions on cardiovascular disease incidence in Chinese middle-aged and elderly population: A nationwide prospective cohort study.

Background: Previous studies indicated that metabolic heterogeneity of obesity would affect the risk of cardiovascular disease (CVD). However, the alterations in CVD risk associated with transitions between various metabolic health statuses influenced by obesity status remain unclear.

Methods: We utilized data from the China Health and Retirement Longitudinal Study (CHARLS), a longitudinal cohort study involving Chinese residents aged 45 years and older. Baseline data were collected in 2011-2012, with follow-up surveys conducted up to 2020. Participants in the study were categorized into four body mass index-metabolic phenotypes: metabolically healthy normal weight (MHNW), metabolically healthy overweight/obesity (MHOO), metabolically unhealthy normal weight (MUNW) and metabolically unhealthy overweight/obesity (MUOO). Transitions in these phenotypes over 4 years were analysed. Cox regression models were used to assess the associations of these phenotypes and their transitions with CVD incidence.

Results: Among 7721 participants, 1353 (17.5%) developed CVD during the follow-up period. Both overweight/obese and metabolically unhealthy statuses were associated with increased CVD risk. The highest risk was observed in the MUOO group (hazard ratio [HR]: 1.74, 95% confidence interval [CI]: 1.50-2.09, p < 0.0001), followed by the MUNW (HR 1.35, 95% CI: 1.13-1.66, p < 0.001) and MHOO (HR: 1.29, 95% CI: 1.08-1.56, p = 0.002) groups compared to the MHNW group. The deteriorations of obesity and metabolic health status elevated the incidence of CVD, whereas improvements in these statuses reduced the risk of CVD. Additionally, alterations in metabolic health status conferred greater benefits in overweight/obese individuals compared to those with normal weight.

Conclusion: The study highlights the importance of maintaining and promoting metabolic health, particularly in overweight/obese individuals, to reduce CVD risk. Metabolic health status plays a more crucial role than obesity status in predicting CVD incidence.