Real-world patient experience with medicinal cannabis use for symptom management in an Australian advanced cancer setting: a mixed method, cohort study using the theory of planned behaviour framework.

Purpose: Patient hesitancy to use MC due to the fear of negative social implications leads to intentional non-adherence and compromises therapeutic outcomes. Hence, we aimed to determine the rate of patient adherence to MC and explore factors influencing patient MC use.

Methods: Demographic and quantitative data related to MC usage were extracted from medical records for patients prescribed MC at a single cancer centre in metropolitan Sydney. Qualitative data was generated from semi-structured interviews. Interview guides were developed based on the Theory of Planned Behaviour (TBP) domains (i.e. Attitudes, Subjective Norms, Behavioural Intention and Perceived Behavioural Control) to elucidate themes influencing MC use. A mixed method approach involving triangulation of quantitative and qualitative methods was used for data analysis.

Results: Twenty patients were included in the study, and the majority of patients showed adherence (n = 14, 70%). The MC formulation used (p = .018), symptom relief (p = .001) and side effects experienced (p = .007) significantly influenced MC adherence. In addition to side effects experienced, findings for barriers to adherence were convergent or complementary for other medication-related factors, including the inconvenience of MC co-administration with food, cost and unpleasant taste.

Conclusions: MC adherence is influenced by its effectiveness for symptom relief whereby appropriate MC formulation selection is crucial and should be determined by the indication (or symptom clusters). Social factors such as the views and experiences of close others had little bearing on MC adherence.