Buchwald H et al. (2004) Bariatric surgery: a systematic review and meta-analysis. JAMA 292: 1724–1737

Around two-thirds of the US population are overweight (BMI ≥25) and 5% are morbidly obese (BMI ≥40 or BMI ≥35 with significant comorbidities). Various surgical procedures—collectively known as bariatric surgery—have been developed for morbidly obese patients who do not respond to diet or drug therapy. A recent systematic review and meta-analysis has looked for the first time at the effect of such interventions on common comorbidities, namely diabetes, hyperlipidemia, hypertension and obstructive sleep apnea.

Buchwald et al. combined the results from 136 studies (22,094 patients) of gastric banding or bypass, gastroplasty, biliopancreatic diversion or other forms of bariatric surgery. Patients lost a mean of 61.2% of their excess weight following surgery—often in excess of 45 kg—and operative mortality was low compared with that for other major surgical procedures. Diabetes was resolved or improved in 86.0% of patients, and this was apparent only days after surgery in some cases. Hyperlipidemia was improved in at least 70.0% of patients. Hypertension and obstructive sleep apnea were resolved or improved in 78.5% and 83.6% of individuals, respectively.

In summary, the majority of obese patients undergoing bariatric surgery achieved improvement or reversal of these common comorbidities. The authors comment that these benefits, along with weight loss, were likely to increase life expectancy at relatively low risk.