Clinical Question: How effective is bariatric surgery in the long term?

Setting: Population-based

Study Design: Nonrandomized controlled trial

Allocation: Unconcealed

Synopsis: According to the results of a recent meta-analysis, bariatric surgery successfully treats many of the comorbid conditions associated with obesity. However, most of the studies were of less than two years’ duration (Buchwald H, et al. Bariatric surgery: a systematic review and meta-analysis. JAMA October 13, 2004;292:1724–37).

In the current study, Swedish researchers invited patients to undergo bariatric surgery. Of 8,966 patients who met age and weight-for-height criteria, 4,047 eventually underwent surgery at one of 25 centers. The decision to have surgery was made by the patient after consultation with a surgeon; patients choosing not to have surgery became part of a control pool. The type of surgery was determined by the physicians at the center. At the time of surgery, each patient was matched with a patient from the control pool based on age, obesity, comorbidities, and other clinical factors. Patients were then followed for up to 10 years. Thus, this was not a randomized trial.

The operative mortality rate was 0.25 percent and the rate of serious surgical complications was 13 percent. Weight loss peaked after one year in the surgery group (38 percent for gastric bypass, 27 percent for vertical banded gastroplasty, and 21 percent for banding). Weight loss at two years was an average of 23 percent for the surgery groups compared with a 0.1 percent weight gain in the control group. After 10 years, weight loss was less dramatic (25, 16, and 13 percent for the three different procedures), but still better than the 1.6 percent gain in the control group.

At two and 10 years, surgical patients were significantly more likely than control patients to have recovered from diabetes (36 versus 13 percent), hypertension (19 versus 11 percent), and hypertriglyceridemia (46 versus 24 percent). There was no difference at two or 10 years in the rate of recovery from elevated total cholesterol. The most important outcome, however, was all-cause mortality. The authors did not give these results because the study is continuing under the supervision of a data-monitoring committee, which suggests that there are no important differences among the groups so far.

Bottom Line: Bariatric surgery helps patients lose weight and reverse diabetes, hypertension, and some hyperlipidemias. It is still unknown whether it affects all-cause mortality. (Level of Evidence: 2c)