1161-P: Are There Sex-Differences in Response to Metabolic/Bariatric Surgery among Adolescents with Severe Obesity?

Bariatric surgery is safe and effective for adolescents, but sex-differences are difficult to examine owing to female predominance in individual studies. We pooled data from four high-quality studies to examine sex-differences among adolescent bariatric surgery. Data from three prospective observational studies and one randomized trial in the United States (Teen-LABS, FABS5+) and Sweden (AMOS, AMOS2), were harmonized. Descriptive statistics explored changes in standard body mass index (BMI) categories over time. We evaluated sex differences in % change in BMI using linear mixed effects models. 389 participants (278 females; 111 males; aged 16.9±1.5 years; 76.6% Non-Hispanic White) were used for analysis. Baseline BMI was 50.5 kg/m² for females and 53.8 kg/m² for males with 79.7% having gastric bypass, 16.7% sleeve gastrectomy, and 3.6% gastric banding. Severe obesity was ubiquitous among participants pre-operatively (M: 100%, F: 99.6%). At 24 months, 40%, 35%, 15%, and 6% of males, 29%, 36%, 21%, and 10% of females were in severe obesity, obesity, overweight, and normal weight categories, respectively. Mean BMI change for females and males, respectively was -22.5% and -25.5% at 6 months, -31.59% and -34.15% at 12 months, and -29.68% and -32.73% at 24 months. A greater BMI reduction was observed among males at 6 months (-2.99%, 95%CI: -5.16, -0.81%, p=0.01), 12 months (-2.56%, 95%CI: -4.52, -0.60, p=0.01), and 24 months (-3.05%, 95%CI: -6.09, -0.01, p=0.05). After adjusting for age, race/ethnicity, and types of procedure, a greater BMI reduction among males at 6 months (-1.95%, 95%CI: -3.77, -0.12, p=0.04), 12 months (-2.10%, 95%CI: -3.89, -0.31, p=0.02), and 24 months (-2.45%, 95%CI: -5.34, 0.43, p=0.10) was still observed. While weight loss following bariatric surgery is significant among both sexes up to 2 years, males consistently exhibit somewhat greater BMI reduction. The clinical relevance and mechanisms driving sex-differences warrant further exploration.