Evaluation of the Association Between Preoperative Clinical Factors and Long-term Weight Loss After Roux-en-Y Gastric Bypass.

Importance: Weight loss after bariatric surgery varies, yet preoperative clinical factors associated with long-term suboptimal outcomes are not well understood.

Objective: To evaluate the association between preoperative clinical factors and long-term weight loss after Roux-en-Y gastric bypass (RYGB).

Design, Setting, and Participants: From June 2001 to September 2007, this retrospective cohort study followed up RYGB patients before surgery to 7 to 12 years after surgery. The setting was a large rural integrated health system. Of 1033 eligible RYGB patients who consented to participate in longitudinal research and completed surgery before October 2007, a total of 726 (70.3%) had a weight entered in the electronic medical record 7 or more years after surgery and were included in the analyses after exclusions for pregnancy and mortality. Date of the long-term weight measurement was recorded between August 2010 and January 2016.

Main Outcomes and Measures: The primary outcome was percentage weight loss (%WL) at 7 to 12 years after surgery. Preoperative clinical factors (>200) extracted from the electronic medical record included medications, comorbidities, laboratory test results, and demographics, among others.

Results: Among the 726 study participants, 83.1% (n = 603) were female and 97.4% (n = 707) were of white race, with a mean (SD) preoperative body mass index (calculated as weight in kilograms divided by height in meters squared) of 47.5 (7.4). From the time of surgery to long-term follow-up (median, 9.3 postoperative years), the mean (SD) %WL was 22.5% (13.1%). Preoperative insulin use, history of smoking, and use of 12 or more medications before surgery were associated with greater long-term postoperative %WL (6.8%, 2.8%, and 3.1%, respectively). Preoperative hyperlipidemia, older age, and higher body mass index were associated with poorer long-term postoperative %WL (-2.8%, -8.8%, and -4.1%, respectively).

Conclusions and Relevance: Few preoperative clinical factors associated with long-term weight loss after RYGB were identified. Preoperative insulin use was strongly associated with better long-term %WL, while preoperative hyperlipidemia, higher body mass index, and older age were associated with poorer %WL. Our findings provide additional insight into preoperative identification of RYGB patients at higher risk for long-term suboptimal outcomes.