Reliability of a self-reported questionnaire assessing the use of cannabis products to treat chronic pain

Background : Cannabis-based products are increasingly used worldwide for chronic pain. However, there is a lack of reliable instruments assessing cannabis exposure. Objective : To develop a questionnaire measuring the use of cannabis to manage chronic pain and assess its reliability. Method : A 24-item questionnaire assessing pain conditions, the type of cannabis products that were used, the methods of use, the concentration of main cannabinoids, and the use of other pain therapies was developed. An expert committee was convened to enhance the content validity of the questionnaire, to improve it, and a longitudinal survey was conducted to test the test-retest reliability of the final version. A two-round survey of 158 participants with chronic pain was conducted between November 2023 and January 2024. Kappa and weighted kappa coefficients were calculated to assess the agreement between the responses of the two rounds. According to the criteria of Landis and Koch, items with a kappa ≥ 0.61 were considered as having a high reliability. Results : The average age of participants was 38 years and the proportion of females was 53.5%. Most of the items assessing the use of cannabis products yielded a high reliability (kappa ≥ 0.61). Items with moderate reliability (0.41 ≤ Kappa < 0.61) included the type of pain and the type of cannabinoids used. Conclusion : The results suggest that the questionnaire developed in this study is a reliable tool for assessing cannabis use in patients with chronic pain in clinical or research settings.