High BMI Not Needed to Benefit from Bariatric Surgery

In 1991, the National Institutes of Health established guidelines for bariatric surgery that require a candidate to have a BMI of greater than 35, accompanied by significant medical comorbidities, or a BMI greater than 40 with no associated medical conditions. However, recent studies suggest that these criteria may exclude patients who could benefit from bariatric surgery.

Researchers compared the results of surgeries conducted on patients who met the NIH criteria with patients who had a BMI of less than 35 and found that low-BMI patients lost just as much weight and had similar resolution of comorbidities with no increase in complications.

One such study looked at 210 patients who underwent gastric lap-band procedures. All subjects were followed for five years after surgery. The study found that excess weight loss averaged 71% for all patients, and 89% of obesity-related complications were resolved.

Of the 210 patients who underwent bariatric surgery, 66 had a BMI of 30 to 35 with significant comorbidities or a BMI of 35 to 40 with no comorbidities. The results of these low-BMI patients were compared to those of 438 historical patients who met the NIH guidelines. After 3 months, low-BMI patients showed a 20.3% excess weight loss, compared to 18.4% excess weight loss in patients meeting NIH criteria. After 18 months, the low-BMI patients lost an average of 42.2% of their excess weight, compared to a 42.3% loss in the other group.

In both groups, some patients suffered from diabetes, hypertension, hyperlipidemia, sleep apnea, arthritis, gastroesophageal reflux disease, or stress urinary incontinence before surgery. Both groups showed a similar percentage of resolution of these conditions following bariatric surgery.

In addition to showing that bariatric surgery can be effective in treating obesity and comorbidities in people with lower BMIs, these studies have also shown that people with lower BMIs are not necessarily at greater risk for complications from surgery. In the study of 66 bariatric surgery patients with low BMIs, there was only a 6% complication rate.