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DALLAS -- There were no differences in mortality after bariatric surgery whether patients regained weight or maintained the loss, according to an analysis of the Swedish Obese Subjects study.

Over a post-surgical 26-year follow-up, there was no excess mortality in those who regained more than 20% of their maximal weight loss within 4 years of surgery compared with those who maintained their weight loss, meaning they regained less than 20% (adjusted HR 0.97, 95% CI 0.79-1.18, P=0.724), reported Markku Peltonen, PhD, of the Finnish Institute for Health and Welfare's Chronic Disease Prevention Unit in Helsinki.

The total mortality incidence rate was 12.4 per 1,000 person-years for both groups, Peltonen noted during his presentation at the ObesityWeek annual meeting. "This was surprising to me. I don't really have a good explanation for this. This was independent of the degree of initial weight loss."

For the most part, this also held true when it came to morbidity in the decades following surgery, but there were modestly higher numerical incidence rates of cardiovascular disease among regainers (9.2 vs 8.7 per 1,000 person-years), as well as cancer (11.3 vs 10.4 per 1,000 person-years), although these differences weren't statistically significant.

In addition, there was a significantly higher incidence of microvascular disease in regainers compared with maintainers (11.0 vs 8.7 per 1,000 person-years, P=0.49).

Peltonen noted that study participants were closely followed for so many years, and therefore, were well monitored. "Even the regain group, after 15 years, they still managed to maintain weight loss of roughly 10% compared to the maintain group who were around 20%," he said. Essentially, it's possible that this smaller, yet maintained, weight loss was enough to offset excess mortality and morbidity.

Data for the analysis came from 1,348 patients (mean age at baseline 48, 70% women) from the surgery group of the prospective . Types of bariatric surgery included gastric bypass, vertical-banded gastroplasty, and nonadjustable or adjustable banding. Of these patients, 631 were deemed to be weight-loss maintainers, and 715 were regainers. At the time of surgery, the average body mass index (BMI) was around 42, and 20% had diabetes.

One year following bariatric surgery, maintainers and regainers lost 25.0% and 24.0% of body weight, respectively. At this time point, both groups dropped down to a BMI of 32.

From 1-year post-op to year 4, maintainers had a -0.2% weight regain, whereas regainers put back on 14.8% of their body weight. At this time, maintainers kept their BMI of 32, while regainers went back up to a BMI of 36.

In a second analysis of this dataset, Peltonen said his group further divided bariatric surgery maintainers and regainers according to how substantial their initial weight loss was -- either large or small. One year after surgery, the "large" group lost around 33% of their body weight, while the "small" group lost around 17%.

Overall, patients who initially lost a large amount of weight in the first year after surgery -- whether they regained it or not -- had a numerically lower total mortality incidence over the near 30-year follow-up. However, there weren't any significant differences in mortality among the subgroups of initial weight loss or maintenance status:

• Small initial, maintainers: incidence rate 14.2 per 1,000 person-years
• Small initial, regainers: 12.9 per 1,000 person-years
• Large initial, maintainers: 11.9 per 1,000 person-years
• Large initial, regainers: 10.8 per 1,000 person-years

Following the same pattern, there were no significant differences in the incidence of cardiovascular disease or cancer among the subgroups. That being said, those who had a larger initial weight loss and maintained it had a significantly lower incidence of microvascular disease, at nearly half the rate of the small, regainer group (7.3 vs 13.7 per 1,000 person-years).

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