2 Evidence gaps

This section describes the evidence gaps, why they need to be addressed and their relative importance for future committee decision making.

The committee will not be able to make a positive recommendation without the essential evidence gaps (see section 2.1) being addressed. Companies can strengthen their evidence base by also addressing as many other evidence gaps (see section 2.2) as possible. Addressing these will help the committee to make a recommendation by better understanding the patient or healthcare system benefits of the technology.

2.1 Essential evidence for future committee decision making

Change in weight

Evidence of sustained long-term weight loss is needed to evaluate the benefits for people using the technologies, because obesity is a chronic condition.

Monitoring and reporting adverse events

Obesity is a complex condition and people may have additional comorbidities including mental health issues. The committee had concerns about risk management and safety monitoring of the technologies, particularly in people taking weight-management medicine. Evidence on how the technologies monitor and report adverse events is needed to evaluate the safety of these technologies.

Resource use

To evaluate the cost effectiveness of the technologies, further information is needed on:

  • healthcare resource use, including number and type of healthcare appointments, NHS staff time needed to support using the technologies, the cost of the weight-management medicine, and referral to bariatric surgery

  • costs associated with implementing and maintaining the use of the technologies in an NHS pathway

  • cost estimates for multidisciplinary weight-management services.

2.2 Evidence that further supports committee decision making

Adherence and completion

More evidence is needed on adherence and completion rates for people using the technologies, to:

  • assess if adherence has any effect on clinical benefit

  • inform future economic modelling

  • understand if adherence is different in particular groups.

The reasons for stopping using a technology are also important to understand. Information on patient characteristics is also needed to evaluate differences in access to the technologies and the potential impact on health inequalities.

Health-related quality of life and psychological outcomes

There is a high burden of mental health issues in people with obesity. Additional data collection is needed using specific patient-reported outcome measures on health-related quality of life and for psychological outcomes such as anxiety or depression and eating disorders. This will support evaluation of the technologies' impact on mental wellbeing using consistent outcomes.