The theory of planned behavior partly explains why adults with chronic musculoskeletal pain consider using medical cannabis for pain management

Chronic musculoskeletal (MSK) pain has multiple causes and a high prevalence. Frequently, pharmacological options do not provide optimal pain relief, and treatment with opioids may lead to serious adverse effects. Although pharmacological effects of cannabis in pain management have been recognized, knowledge about a person’s motivations regarding this therapeutic strategy is limited. Such knowledge is important, given possible serious adverse effects of cannabis, and an increasing trend for self-medication. Our study aimed at exploring, understanding and quantifying pain patients’ motivations, concerns and needs regarding the use of medical cannabis for pain management. Thus, a questionnaire study, based on the Theory of Planned Behavior (TPB), was performed. The TPB’s contribution to the understanding of health-related behaviors has been widely recognized. In a prior, purely qualitative part of this research, semi-structured interviews were conducted with adults affected by chronic MSK pain in Canada. Using the results of these interviews, a questionnaire was developed and validated in a pilot step. This questionnaire aimed at quantifying which TPB elements relate to the intention to use medical cannabis for the management of chronic MSK pain. It also included questions on pain and personal characteristics, assessed through validated scales. Among 226 persons who completed this online questionnaire, 160 could be included in final analyses. The adjusted and reduced TPB based model explained 51% of the intention to use medical cannabis to manage chronic MSK pain. The explanatory exogenous factors of this model were current pain, prior experience of pain reduction and prior cannabis use. Normative, control and behavior beliefs were also included in the final model. These beliefs related to subjective norms, perceived ability, and attitudes, which in turn were associated with the behavioral intention. The study results are relevant for adults suffering from chronic MSK pain and their health professionals, when making decisions on the use of medical cannabis to manage this condition. Given possible serious adverse effects of cannabis and the growing trend for self-medication, these results should be tested for other indications and on other populations, to help patients’ and prescribers improve use of medical cannabis.