Green Book

Appendix B

The COM-B model

COM-B (capability, opportunity, motivation and behaviour) is a simple model to understand behaviour. This model recognises that behaviour is part of an interacting system involving all these components (Figure B1). It can help identify the sources of a behaviour that could be an appropriate target for an intervention. It can also be used to understand (and overcome) barriers.1

Using COM-B: Example

Your practice has identified that patients with mental health disorders are at increased risk for cardiovascular disease (CVD), in part due to low levels of physical activity. The practice team would like to offer support to these patients to increase their physical activity. This means that GPs in your practice need to change current patient behaviour and offer physical activity interventions to patients with mental health issues.

Using COM-B, you identify the following:

  • Capability – GPs in the practice don’t know what services are available for patients with mental illness.
  • Motivation – GPs don’t feel comfortable burdening their patients.
  • Opportunity – GPs feel that they don’t have time in a standard appointment to offer behavioural support to increase physical activity, particularly in patients with low motivation levels.

This gives your practice a starting point for where to focus when planning an intervention. In this case, you would look to improve:

  • capability, by ensuring GPs know what the effective physical activity interventions are for this group of patients, what services and resources are available to provide these, and how to access them (refer to the RACGP’s HANDI, ‘Exercise: Depression’)
  • GP motivation, by providing good quality evidence of benefit of physical activity in patients with mental health issues (to increase belief that it is a good thing to do) and highlighting the negative consequences of not doing it (similar to the decision balance process of motivational interviewing [MI])
  • opportunity, by having more time to do it (longer appointment times) and having all members of the team involved (spreading the workload and being part of a ‘crowd’ who are doing it).