Abstract P327: Increased Physical Activity in Adolescents Post-Weight Loss Surgery is Associated with Improvements in CVD-Related Lipid Measures

Abstract

Introduction: Severe obesity is increasing in adolescents and is strongly associated with CVD risk. Weight loss surgery (WLS) effectively treats severe obesity and improves CVD-related lipid measures. Independent of weight loss (WL), physical activity (PA) also improves lipid-related CVD measures and is key to WL maintenance. Longitudinal PA behaviors post-WLS and the impact on CVD-related lipid measures in adolescents is unclear, in part because PA data are largely self-reported. Hypothesis: We assessed the hypothesis that PA improves plasma lipids beyond that associated with active WL in adolescents, post-WLS. Methods: We used objective StepWatch TM PA data from 108 participants of the Teen-LABS bariatric surgery study from baseline to 3 years post-WLS. Inclusion criteria included 1) at least 3 days (1 weekend day and 2 weekdays) of recorded StepWatch TM data, including 6 hours or more of continuously recorded data per day, 2) at least 10 steps per hour, 3) data at baseline and one or more postoperative time points (6 months, 1 year, 2 years and/or 3 years), and 4) matched laboratory and anthropometric data. Participants on lipid lowering therapy were excluded. The primary outcome of interest was absolute change in plasma lipids (TC, TG, HDL-C, LDL-C, and non-HDL-C), holding sex, race, time, % change in iliac waist circumference and procedure constant in a linear regression model with generalized estimating equations assuming an exchangeable working correlation structure. PROC TRAJ in SAS was used to determine the optimal number of group activity trajectories based on step counts at all visits. Results: Two activity groups were identified from PROC TRAJ : less and more active. When considering all mean daily step count data, the overall mean was 4241 (95% CI: 3970, 4513), the more active trajectory mean was 8494 (95% CI: 7596, 9392), and the less active trajectory mean was 3722 (95% CI: 3530, 3915), all well below the recommended 12,000 steps for age. Yet statistically and clinically significant differences by activity trajectory emerged. Greater absolute decreases in LDL-C and non-HDL-C (-15 mg/dL [95% CI: (-28, -2)], p =0.026 and -15 mg/ld. [95% CI: (-28, -1)], p = 0.035), respectively, were associated with activity, holding stated co-variables constant. Activity was also associated with greater percentages of TG, LDL-C and non-HDL-C values being within acceptable ranges, by 2011 NIHLB Integrated Criteria, at 2 years, (TG, 83% vs 70%; LDL-C, 100% vs 83%; non-HDL-C, 83% vs 70%). Conclusion: In conclusion, greater improvement in CVD-related lipid measures was associated with more activity 2 years post-WLS in adolescents, one year post-active WL. Of great interest, the predominant lipid measure influencing CVD risk post-WLS was not HDL-C, as reported in adults. Importantly, the PA-associated reductions of LDL-C, and non-HDL-C are more strongly associated with improved CVD risk than HDL-C increase.