Association of Patient Age at Gastric Bypass Surgery With Long-term All-Cause and Cause-Specific Mortality

Abstract

Importance: Bariatric surgery is effective in reducing all-cause and cause-specific long-term mortality. Whether the long-term mortality benefit of surgery applies to all ages at which surgery is performed is not known.

Objective: To examine whether gastric bypass surgery is equally effective in reducing mortality in groups undergoing surgery at different ages.

Design, setting, and participants: All-cause and cause-specific mortality rates and hazard ratios (HRs) were estimated from a retrospective cohort within 4 categories defined by age at surgery: younger than 35 years, 35 through 44 years, 45 through 54 years, and 55 through 74 years. Mean follow-up was 7.2 years. Patients undergoing gastric bypass surgery seen at a private surgical practice from January 1, 1984, through December 31, 2002, were studied. Data analysis was performed from June 12, 2013, to September 6, 2015. A cohort of 7925 patients undergoing gastric bypass surgery and 7925 group-matched, severely obese individuals who did not undergo surgery were identified through driver license records. Matching criteria included year of surgery to year of driver license application, sex, 5-year age groups, and 3 body mass index categories.

Intervention: Roux-en-Y gastric bypass surgery.

Main outcomes and measures: All-cause and cause-specific mortality compared between those undergoing and not undergoing gastric bypass surgery using HRs.

Results: Among the 7925 patients who underwent gastric bypass surgery, the mean (SD) age at surgery was 39.5 (10.5) years, and the mean (SD) presurgical body mass index was 45.3 (7.4). Compared with 7925 matched individuals not undergoing surgery, adjusted all-cause mortality after gastric bypass surgery was significantly lower for patients 35 through 44 years old (HR, 0.54; 95% CI, 0.38-0.77), 45 through 54 years old (HR, 0.43; 95% CI, 0.30-0.62), and 55 through 74 years old (HR, 0.50; 95% CI, 0.31-0.79; P < .003 for all) but was not lower for those younger than 35 years (HR, 1.22; 95% CI, 0.82-1.81; P = .34). The lack of mortality benefit in those undergoing gastric bypass surgery at ages younger than 35 years primarily derived from a significantly higher number of externally caused deaths (HR, 2.53; 95% CI, 1.27-5.07; P = .009), particularly among women (HR, 3.08; 95% CI, 1.4-6.7; P = .005). Patients undergoing gastric bypass surgery had a significantly lower age-related increase in mortality than severely obese individuals not undergoing surgery (P = .001).

Conclusions and relevance: Gastric bypass surgery was associated with improved long-term survival for all patients undergoing surgery at ages older than 35 years, with externally caused deaths only elevated in younger women. Gastric bypass surgery is protective against mortality even for older patients and also reduces the age-related increase in mortality observed in severely obese individuals not undergoing surgery.

Figure 1. All-Cause Mortality Hazard Ratios by Age and Surgery Group

All-cause mortality hazard ratios of each study group and age-at-surgery group relative to the referent group of non-operated, severely obese subjects younger than 35. GB: gastric bypass surgery. Non-GB: non-operated, severely obese subjects. Error bars represent 95% confidence intervals.

Figure 2. Mortality Hazard Ratios for Externally-Caused Deaths by Age and Surgery Group

Mortality hazard ratios for externally caused deaths of each study group and age-at-surgery group relative to the referent group of non-operated, severely obese subjects younger than 35. GB: gastric bypass surgery. Non-GB: non-operated, severely obese subjects. Error bars represent 95% confidence intervals.