Neighborhoods matter: contextual determinants of bariatric surgery utilization and weight loss in Washington, D.C.

INTRODUCTION: Bariatric surgery is the most effective durable treatment for severe obesity, yet neighborhood context may shape both progression to surgery and the ability to sustain postoperative health behaviors. We examined bariatric surgery utilization and postoperative body mass index (BMI) change in relation to tract-level food insecurity and neighborhood vulnerability in Washington, DC. METHODS: Retrospective EHR-based cohort study of adult Washington, DC residents with BMI data and census tract linkage (2020-2023). Bariatric referral/order, consultation, and completed surgery were identified; BMI measures were linked to tract-level indicators of food insecurity, poverty, social vulnerability, and deprivation. We compared surgical and non-surgical patients; mapped tract-level BMI change using choropleth maps; identified space-time clusters of utilization using retrospective scan statistics; and compared social determinants between high- and low-utilization clusters using analysis of variance. RESULTS: Among 41,617 adult obese DC residents, 1,129 (2.7%) had a bariatric referral/order, 1,952 (4.7%) had a bariatric consultation, and 472 (1.1%) underwent surgery. Surgical patients were predominantly Black/African American (90%); concentrated in Wards 5 (31%), 7 (34%), and 8 (30%). Tract-level BMI patterns were more favorable among surgical than non-surgical patients. Space-time analysis identified two high- and two low-utilization clusters. Compared with low-utilization clusters, high-utilization clusters had higher food insecurity (88.1 vs. 5.4%; p < 0.001), poverty (81.0 vs. 27.6%; p < 0.001), uninsured rates (5.1 vs. 2.4%; p < 0.001), and overall social vulnerability (10.5 vs. 5.8; p < 0.001), Neighborhood Deprivation Index (1.533 vs. - 0.721); all four SVI subdomains were higher (p < 0.001, except housing type and transportation, p = 0.019). CONCLUSION: Bariatric surgery utilization clustered in neighborhoods with high structural and social vulnerability and postoperative BMI reduction was observed across neighborhoods. Incorporating neighborhood context into bariatric care may help identify areas for targeted referral, access support, and postoperative resource allocation to promote equitable treatment.