Weights and measures: are bariatric surgery guidelines realistic?

Obesity is a public health pandemic; known to be itself a cause for increased morbidity and mortality, it also adversely impacts other conditions such as type 2 diabetes, cardiovascular disease and cancer. Surgery, compared to non-invasive interventions, offers significantly more benefits for patients and has major cost savings for the National Health Service. ¹ The National Institute for Health and Care Excellence recently drafted its latest eligibility guidelines, ² bringing them into line with others worldwide. A key question remains, however; will the new guidelines cause an increase in the number of people eligible for bariatric surgery, and if they do, can the National Health Service meet this demand?

In the United Kingdom, the proportion of adults with obesity has significantly increased in recent decades, with no signs of any reversal in this trend; ³ this is despite the UK government ambitiously announcing in 2007 that England was to be the first country to reverse the trend in rising rates of obesity trend and the introduction of public health programmes such as ‘Healthy Lives, Healthy People’ (DoH 2008) and ‘Change4Life’ (DoH 2009).

The failure of public health and medical interventions ⁴ to reduce the burden of obesity has led to increased interest in surgical interventions. Bariatric surgery is superior to non-surgical techniques for the management of obesity; apart from reporting better quality of life, surgically-treated patients lose more weight, experience better control of their type 2 diabetes, have improved serum lipid profiles and have lower all-cause mortality. ⁵

Eligibility criteria for bariatric surgery among UK, EU, US, Canadian and Australian services are very similar. All advocate surgery in patients in whom lifestyle modification has failed and have a body mass index ≥40 or in those with body mass index ≥35 with an obesity-related co-morbidity; the US guidelines give a comprehensive list of these co-morbidities. All guidelines also suggest that patients with a body mass index ≥30 and poorly-controlled type 2 diabetes or metabolic syndrome may be considered for bariatric surgery, if deemed beneficial.

The publication of these guidelines will inevitably mean more people will become eligible for surgery, but will these guidelines be practical; and can health services cope with the potential demand for bariatric surgery? The proportion of people with class III obesity (body mass index ≥40), who are automatically eligible for surgery, has been steadily increasing in the UK for many years and currently stands at 1.7% of men and 3.1% of women, with one projection indicating that this could reach 3% of men and 6% of women by 2030. ⁶ Furthermore, the number of people eligible for bariatric surgery in the UK is likely to have been underestimated ⁷ ; concurrent data from Canada show that bariatric surgery not only has the longest wait times of any common surgically-treated condition ⁸ but that there are also 600 times more procedures required than there is capacity to deliver. ⁹ Canadian and UK healthcare systems and population demographics are similar, but with the UK population almost twice as large, are we about to see a huge surge in our own bariatric surgery rates? Will we need more bariatric-equipped theatres, wards, surgeons and nurses to meet this demand? Can we realistically meet the demand given the current financial state of the National Health Service in the UK?

The danger is that guidelines which do not take into account the capacity of their health system to provide a service – or provide recommendations on what volume of services a health system should offer – will lead to increased variability in clinical practice as funders of healthcare may ignore guidance on treatments they do not have the capacity – or funding – to treat.

So what can we do? A recent study in a representative UK population provided the first robust evidence that despite commonly held beliefs, body mass index by itself is not a good indicator for predicting mortality. Work by Padwal and colleagues demonstrated that although the all-cause mortality at 10 years was 2.1% for the bariatric surgery-eligible population, the presence of type 2 diabetes was the single biggest risk factor for mortality. They suggest that the presence of type 2 diabetes should be the decisive factor when considering bariatric surgery as opposed to adhering to strict body mass index guidance. ¹⁰

National guidelines in different countries have reached similar conclusions about the eligibility for bariatric surgery in people with obesity; however, their health systems' capacity to meet their eligibility standards has been overlooked. This raises questions about whether the role of guidance bodies (for example, National Institute for Health and Care Excellence) should also include an assessment of the capacity of a health system when deciding whether or not an intervention that is specified in their guidelines is deliverable.

While the new guidelines may offer an easy and apparently logical way to allocate bariatric services, the limitations of body mass index as a measure of obesity, underestimation of eligibility and therefore the underestimation of future demand may well lead to increased pressures on health services. Without action now to boost bariatric services or re-think guidelines with emphasis on co-morbidities as opposed to body mass index, we may produce guidelines that the National Health Service has no ability to meet.