Patients who have undergone bariatric surgery are at substantially increased risk of suicide, a study from the United States has found. Although the absolute suicide rate (1 in 538) was low, this was much higher than that of the general population.

All Pennsylvania residents who underwent bariatric surgery between January 1st 1995 and December 31st 2004 were identified from the comprehensive state records. This data was then matched to mortality data for the period September 1st 1996 to December 28th 2006.

Of the 16,683 patients who underwent bariatric surgery, 31 committed suicide during the study period. The suicide rates for men and women were 13.7 and 5.2 per 10,000 person-years respectively. The corresponding age-matched rates for the US population were 2.4 (men) and 0.7 (women) per 10,000 person-years.

The true number of suicides is likely to have been significantly higher as a result of the misclassification of suicides as unintentional poisoning. While the official US suicide rate declined by 12% between 1987 and 2006, there was a more than four-fold increase in the number of deaths attributed to unintentional poisoning.1

It is possible that the increased suicide risk was due to the characteristics of the patients selected for bariatric surgery rather than the surgery itself. There is a bidirectional relationship between obesity and depression: obese patients are more likely to become depressed, and depressed patients are more likely to become obese.2 Low socio-economic status is associated with both obesity3 and an increased risk of suicide.4

Around 30% of suicides occurred within the first two years following surgery, with 69% occurring within three years. However, the highest number of suicides (39%) occurred during the third year after surgery, and the authors point out that this is the time when patients often start to regain weight.

There are a number of reasons why patients may be disappointed with the results of surgery: failure to achieve the anticipated weight loss, cosmetic problems because of redundant skin, persistent gastrointestinal symptoms,5 or the discovery that their unhappiness and low self-esteem has a more complex basis than obesity alone.

NICE has concluded that bariatric surgery is beneficial for obese patients with a BMI ≥40, or between 35 and 40 if they have a co-existing disease (e.g. diabetes, hypertension or sleep apnoea) which could be improved by weight loss. All non-surgical methods should have been tried, without success, and patients should be fit for surgery and committed to long-term follow-up.6 Over the period 2000-2008, there was a 10-fold increase in the number of bariatric procedures performed in the UK.7

I would draw two lessons from this study. First, before referring patients for bariatric surgery, we must have a detailed discussion with them regarding both the potential benefits and associated risks of surgery, including the risk that they will ultimately be disappointed with the result. Second, we should ensure that bariatric surgery patients receive adequate support and follow-up, particularly during the second and third postoperative years.

Dr Phillip Bland