This study assessed all-cause and specific-cause mortality after Roux-en-Y gastric bypass (RYGB) and in matched control subjects, stratified by diabetes status.
RYGB patients were matched by age, BMI, sex, and diabetes status at time of surgery to nonsurgical control subjects using data from the electronic health record. Kaplan-Meier curves and Cox regression were used to assess differences in all-cause and specific-cause mortality between RYGB patients and control subjects with and without diabetes.
Of the 3,242 eligible RYGB patients enrolled from January 2004 to December 2015, control subjects were identified for 2,428 (n = 625 with diabetes and n = 1,803 without diabetes). Median postoperative follow-up was 5.8 years for patients with diabetes and 6.7 years for patients without diabetes. All-cause mortality was reduced in RYGB patients compared with control subjects only for those with diabetes at the time of surgery (adjusted hazard ratio 0.44; P < 0.0001). Mortality was not significantly improved in RYGB patients without diabetes compared with control subjects without diabetes (adjusted hazard ratio 0.84; P = 0.37). Deaths from cardiovascular diseases (P = 0.011), respiratory conditions (P = 0.017), and diabetes P = 0.011) were more frequent in control subjects with diabetes than in RYGB patients with diabetes. RYGB patients without diabetes were less likely to die of cancer (P = 0.0038) and respiratory diseases (P = 0.046) than control subjects without diabetes but were at higher risk of death from external causes (P = 0.012), including intentional self-harm (P = 0.025), than control subjects without diabetes.
All-cause mortality benefits of RYGB are driven predominantly by patients with diabetes at the time of surgery. RYGB patients with diabetes were less likely to die of cardiovascular diseases, diabetes, and respiratory conditions than their counterparts without RYGB.