2 Research recommendations
- 2.1 Follow-up care after bariatric surgery
- 2.2 Long-term outcomes of bariatric surgery on people with type 2 diabetes
- 2.3 Bariatric surgery in children and young people
- 2.4 Obesity management for people with a condition associated with an increased risk of obesity
- 2.5 Long-term effect of very-low-calorie diets on people with a BMI of 40 kg/m2 or more
The Guideline Development Group has made the following recommendations for research, based on its review of evidence, to improve NICE guidance and patient care in the future.
Do post-operative lifestyle intervention programmes (exercise, behavioural or dietary) improve weight loss and weight-loss maintenance following bariatric surgery?
Lifestyle interventions are targeted pre-operatively with formalised recommendations to prepare patients for surgery. In contrast, post-surgery there are no lifestyle intervention programmes to help patients adapt. Limited evidence suggests that exercise and behavioural input improve weight loss outcomes, but high quality research is needed to assess the impact of these interventions.
What is the long-term effect of bariatric surgery on diabetes-related complications and quality of life in people with type 2 diabetes compared with optimal medical treatment?
Short-term studies (1 to 2 years) show that patients with type 2 diabetes who undergo bariatric surgery lose more weight and have better blood glucose control than those treated with conventional diabetes management. There are no long-term data (that is, over 3 years) to show whether this results in reduced development of diabetes complications and improved quality of life compared with standard care.
What are the long-term outcomes of bariatric surgery in children and young people with obesity?
Monitoring of obesity comorbidities (respiratory problems, atherosclerosis, insulin resistance, type 2 diabetes, dyslipidaemia, fatty liver disease, psychological sequelae) in children and young people with obesity is limited because of the lack of dedicated tier 3 or 4 paediatric obesity services in the UK. Centralised collection of cohort data is lacking in the UK when compared with elsewhere in Europe (Flechtner-Mors 2013) and the USA (Must 2012). Current data on longer‑term outcomes (more than 5 years) in young people undergoing bariatric surgery are also sparse (Lennerz 2014, Black 2013), demonstrating a need for research in this area.
What is the best way to deliver obesity management interventions to people with particular conditions associated with increased risk of obesity (such as people with a physical disability that limits mobility, a learning disability or enduring mental health difficulties)?
People living with learning disabilities or mental health problems or a physical disability that limits mobility have been found to experience higher rates of obesity compared with people who do not have these conditions.
It is estimated that around 23% of children with learning disabilities are obese (Emerson and Robertson 2010). Other studies report rates of obesity in adults with learning disabilities of around 50% (Melville et al. 2007).
Among adults with severe mental illness, the prevalence of obesity has been reported to be as high as 55%. Physical inactivity, unhealthy diets and weight gain from psychotropic medication are all factors that contribute to this. People with serious mental illness have mortality rates up to 3 times as high as the general population. The primary cause of death in these people is cardiovascular disease, which is strongly associated with the incidence of obesity.
There is minimal evidence from controlled studies as to which obesity interventions are effective for people with learning disabilities or mental health difficulties. This lack of evidence contributes to the inequalities around outcomes and access to services as experienced by these people.
What are the long-term effects of using very-low-calorie diets (VLCDs) versus low-calorie diets (LCDs) on weight and quality of life in patients with a BMI of 40 kg/m2 or more, including the impact on weight cycling?
There was little information found in the literature search on the use of VLCDs in patients with a BMI above 40 kg/m2, although they are increasingly used in this group of patients. There was also a lack of data on quality of life. The Guideline Development Group was concerned about VLCDs potential encouraging disordered eating or weight cycling, which is detrimental to both physical and psychological health. It would also be useful to differentiate between liquid VLCDs and those VLCDs which incorporate solid food products to identify whether the liquid formulation or the energy reduction alone affected weight loss, quality of life, and subsequent disordered eating.