Studies on bariatric surgery: duration and follow-up

Many studies on bariatric surgery have been published to date. What is the maximum duration of the trials and follow-up?

Maria Tiboni: We do have a few observational studies that have looked at outcomes of bariatric surgery in terms of mortality, weight loss, hypertension, diabetes – even economic analysis – that have gone all the way up to 15 years. Probably the best case or the one to mention is the Swedish Obese Subjects study, the study started back in 1987 I believe. The first article [from the study] was published in 2007 in the New England Journal of Medicine. They were able to actually get a follow-up of patients up to 15 years. Unfortunately, [as in] all of the observational studies that are a long-term follow-up, past 10 years of follow-up, there was actually a significant proportion of patients that was lost to follow-up at 10 years and even 15 years.

But in terms of long-term outcomes, observational studies are the only ones we can use to tell us what happens after bariatric surgery. Fortunately, in the last 5 or 6 years we have seen randomized controlled trials, so we can say now that we have better evidence looking at intermediate outcomes after bariatric surgery in terms of glycemia control.