Abstract 10: Metabolically Healthy Obesity Over 25 Years in the Coronary Artery Risk Development in Young Adults (CARDIA) Study: Race and Sex Differences

Abstract

Background: Obesity is heterogeneous condition with phenotypic variation. Metabolically healthy obese (MHO) may represent an unstable phenotype which changes over time. MHO duration, or the length of time in MHO, is not well characterized. The purpose is to quantify MHO duration over 25 years and explore possible race/sex differences. Methods: Young adults (baseline ages 18-30 yrs) from CARDIA were included if they were non-obese at baseline, developed obesity (BMI ≥30kg/m 2 ) at any follow-up exam (yrs 7, 10, 15, 20 and 25), and had complete data for metabolic status, age, race and sex (n=702). MHO was defined as obese (BMI ≥30 kg/m 2 ) and having either 0 or 1 risk factor of the following: ≥SBP/DBP 130/85 mmHg; glucose ≥100 mg/dL; triglycerides (≥150 mg/dL); and HDL-C (men <40, women <50 mg/dL). Obese individuals with ≥2 risk factors were classified as metabolically unhealthy obese (MUO). MHO duration (yrs) and obesity duration (yrs) were estimated for subsequent time-points; and a duration sum was calculated for the follow-up period. For two time-points in which a person remained MHO and obese, a duration for that period was assigned. If they transitioned to MUO or non-obese, then the midpoint of the time period was estimated as MHO duration (yrs). MHO duration was also expressed as the percentage (%) of the total obesity duration. Multivariable adjusted ANCOVA was used to compare MHO duration (%) between race and sex groups (black men, white men, black women and white women), adjusting for baseline age, baseline BMI status (normal weight or overweight). Results: The eligible CARDIA sample was 55% black, 71% women and had a mean (± SD) baseline age of 25.0 ± 3.7 yrs. Duration of obesity was 12.3 ± 6.8 yrs, MHO duration (yrs) was 6.2 ± 5.4 yrs (range: 0 years to 19 yrs), and MHO duration (%) was 51.9 ± 34.8%. After adjusting for age and baseline BMI, MHO duration (%, mean ± SE) was significantly higher in women compared to men within race (black women n=292: 56.3 ± 2.0% vs. black men n=91: 43.3 ± 3.6%, p=0.001; white women n=206: 56.1 ± 2.4% vs. white men n=113: 39.7 ± 3.2%, p <0.0001). No significant differences were found between race groups within gender (black men vs. white men or black women vs. white women). Conclusion: MHO status is a transient phenotype accounting for only approximately half of obesity duration. Women have longer MHO duration compared to men, but differences by race were not apparent. Future research is needed to explore possible modifiable predictors and/or determinants of longer MHO duration in order to maintain a healthy cardiometabolic phenotype, even in the presence of obesity.