Bariatric surgery delivered in routine clinical practice in the UK is associated with a substantial initial weight loss that is sustained for at least four years after surgery, according to a study published in PLOS Medicine. The longitudinal study, conducted by Ian Douglas and colleagues at the London School of Hygiene & Tropical Medicine, UK, also shows that bariatric surgery is associated with improvements in pre-existing type 2 diabetes and hypertension and with a reduced risk of the onset of several obesity-related co-morbidities.
Bariatric surgery has helped obese people lose weight in randomized controlled trials, but the benefits for patients' broader health over a longer period have not been as well studied. Here, the researchers investigated whether there was an association between bariatric surgery and subsequent weight, BMI, and obesity-related illnesses in a study of 3882 bariatric surgery patients and similar control patients who did not have surgery, tracked using primary care records in the UK Clinical Practice Research Datalink. Bariatric surgery patients lost weight at a rate of 4.98 kg/month (95% Confidence Intervals 4.88 to 5.08) during the first four post-operative months (versus no change in the comparision group); their weight loss was sustained at a slower rate for four years. Bariatric surgery was also associated with a reduced risk of getting a new diagnosis of type 2 diabetes (Hazard Ratio with 95% CI: 0.68 (0.55-0.83)), hypertension (0.35 (0.27-0.45)), angina (0.59 (0.40-0.87)), heart attack (0.28 (0.10-0.74)), and obstructive sleep apnea (0.55 (0.40-0.87)). Surgery was also associated with increased resolution of both type 2 diabetes (9.29 (6.84 - 12.62)) and hypertension (5.64 (2.65-11.99) among people who already had these conditions. The investigators did not detect an association between bariatric surgery and reduced mortality in this study, but noted that longer follow-up may be needed to establish associations with mortality.
The accuracy of these findings may be limited by the incomplete recording of some outcomes in primary care patient management records. Nevertheless, these results suggest that widening the availability of bariatric surgery in the UK could provide substantial health benefits for people who are very obese. The authors estimate that, assuming these associations are causal, broader use of bariatric surgery in the UK over four years could prevent or resolve roughly 93,000 cases of hypertension and 149,000 cases of type 2 diabetes.