Changes in patient health questionnaire (PHQ-9) scores in adults with medical authorization for cannabis

Background Legal access to medical cannabis is increasing world-wide. Despite this, there is a lack of evidence surrounding its efficacy on mental health outcomes, particularly, on depression. This study assesses the effect of medical cannabis on Patient Health Questionnaire (PHQ-9) scores in adult...

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Bibliographic Details
Published in:BMC public health 2020-06, Vol.20 (1), p.1-987, Article 987
Main Authors: Round, Jessica M, Lee, Cerina, Hanlon, John G, Hyshka, Elaine, Dyck, Jason R. B, Eurich, Dean T
Format: Article
Language:English
Subjects:
Adults
Antidepressants
Cannabis
Consent
Depression
Ethics
Health aspects
Health surveys
Major depressive disorder
Medical cannabis
Medical marijuana
Medical referrals
Medical research
Mental depression
Mental health
Observational studies
Patient health questionnaire
Patients
PHQ-9
Public health
Questionnaires
Statistical analysis
Studies
Surveys
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Summary:Background Legal access to medical cannabis is increasing world-wide. Despite this, there is a lack of evidence surrounding its efficacy on mental health outcomes, particularly, on depression. This study assesses the effect of medical cannabis on Patient Health Questionnaire (PHQ-9) scores in adult patients between 2014 and 2019 in Ontario and Alberta, Canada. Methods An observational cohort study of medically authorized cannabis patients in Ontario and Alberta. Overall change in PHQ-9 scores from baseline to follow-up were evaluated (mean change) over a time period of up to 3.2 years. Results 37,338 patients from the cohort had an initial PHQ-9 score recorded with 5103 (13.7%) patients having follow-up PHQ-9 scores. The average age was 54 yrs. (SD 15.7), 46% male, 50% noted depression at baseline. The average PHQ-9 score at baseline was 10.5 (SD 6.9), following a median follow-up time of 196 days (IQR: 77-451) the average final PHQ-9 score was 10.3 (SD 6.8) with a mean change of - 0.20 (95% CI: - 0.26, - 0.14, p-value < 0.0001). Overall, 4855 (95.1%) had no clinically significant change in their PHQ-9 score following medical cannabis use while 172 (3.4%) reported improvement and 76 (1.5%) reported worsening of their depression symptoms. Conclusions Although the majority showed no clinically important changes in PHQ-9 scores, a number of patients showed improvement or deteriorations in PHQ-9 scores. Future studies should focus on the parallel use of screening questionnaires to control for PHQ-9 sensitivity and to explore potential factors that may have attributed to the improvement in scores pre- and post- 3-6 month time period. Keywords: Depression, Major depressive disorder, Patient health questionnaire, PHQ-9, Medical cannabis
ISSN:1471-2458
1471-2458
DOI:10.1186/s12889-020-09089-3