Predictors of the transition from metabolically healthy obesity to unhealthy obesity

Purpose: Evidence that metabolically healthy obesity (MHO) is a stable benign condition is unclear. The aim of this study was to estimate the transition of MHO subjects to unhealthy obesity (occurrence of cardio-metabolic events and/or risk factors) and its predictors. Methods: We conducted an explorative follow-up study in a subset of MHO patients > 40 years without any cardio-metabolic risk factors and with normal LDL cholesterol (LDLc) levels, identified among 1530 obese patients. Due to the low sample size, a bootstrap approach was applied to identify the variables to be included in the final multivariate discrete-time logit model. Results: The prevalence of MHO was 3.7%. During the follow-up (mean 6.1 years, SD 2.0), none of the MHO reported cardiovascular events, diabetes or prediabetes; 26 subjects developed risk factors (53% high LDLc and 50% hypertension). At the 6 and 12-year of follow-up, the cumulative incidence of transition to unhealthy obesity was 44% (95% CI 31–59%) and 62% (95% CI 45–79%), the incidence of high LDLc was 23% (95% CI 13–37%) and 40% (95% CI 25–59%) and that of hypertension was 20% (95% CI 11–33%) and 30% (95% CI 17–48%). LDLc and duration of follow-up were independent predictors of the transition from MHO to unhealthy obesity [OR 1.038 (1.005–1.072) and 1.360 (1.115–1.659)]. Conclusions: Results suggest that (a) MHO individuals do not move over time forward diabetes/prediabetes but develop risk factors, such as hypertension and higher LDL c that worsen the cardiovascular prognosis; (b) LDLc and the flow of time independently predict the transition to unhealthy status. Level of evidence: Level III, cohort study.