Higher THC:CBD ratio significantly improves neuropathic pain, insomnia and depression, but not anorexia and PTSD flashbacks; anxiety benefits most from a 1:1 ratio.
Summary
Retrospective real-world study (n=2.431, 26.150 observations): Higher THC:CBD ratio not significantly associated with improvement of PTSD flashbacks OR=1,43 (95% CI 0,60–3,41; p=0,415). Negative finding: THC:CBD ratio without significant benefit for PTSD flashbacks compared to lower ratio.
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PopulationPalliative care patients with neuropathic pain, anorexia, anxiety, depression, insomnia or PTSD flashbacks; n=2.431 (26.150 observations)
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InterventionMedical cannabis with variable THC:CBD ratio (various products, self-reported)
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ControlComparison of different THC:CBD ratios against each other (no placebo control)
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OutcomeHigher THC:CBD ratio significantly associated with response in neuropathic pain (OR 3,58; 95% CI 1,32–9,68; p=0,012), insomnia (OR 2,93; 95% CI 1,75–4,91; p<0,001) and depressive symptoms (OR 1,63; 95% CI 1,07–2,49; p=0,022); no significant effect on PTSD flashbacks, anorexia; anxiety symptoms showed an inverted U with maximum benefit at a 1:1 ratio
Confidence in the evidence
Very lowLowModerateHigh
Moderate
The third of four GRADE levels, the effect estimate is probably reliable.
<b><i>Objectives:</i></b> To determine the relative contributions of tetrahydrocannabinol (THC) and cannabidiol (CBD) to patients' self-ratings of efficacy for common palliative care symptoms. <b><i>Design:</i></b> This is an electronic record-based retrospective cohort study. Model development used logistic regression with bootstrapped confidence intervals (CIs), with standard errors clustered to account for multiple observations by each patient. <b><i>Setting:</i></b> This is a national Canadian patient portal. <b><i>Participants:</i></b> A total of 2,431 patients participated. <b><i>Main Outcome Measures:</i></b> Self-ratings of efficacy of cannabis, defined as a three-point reduction in neuropathic pain, anorexia, anxiety symptoms, depressive symptoms, insomnia, and post-traumatic flashbacks. <b><i>Results:</i></b> We included 26,150 observations between October 1, 2017 and November 28, 2018. Of the six symptoms, response was associated with increased THC:CBD ratio for neuropathic pain (odds ratio [OR]: 3.58; 95% CI: 1.32-9.68; <i>p</i> = 0.012), insomnia (OR: 2.93; 95% CI: 1.75-4.91; <i>p</i> < 0.001), and depressive symptoms (OR: 1.63; 95% CI: 1.07-2.49; <i>p</i> = 0.022). Increased THC:CBD ratio was not associated with a greater response of post-traumatic stress disorder (PTSD)-related flashbacks (OR: 1.43; 95% CI: 0.60-3.41; <i>p</i> = 0.415) or anorexia (OR: 1.61; 95% CI: 0.70-3.73; <i>p</i> = 0.265). The response for anxiety symptoms was not significant (OR: 1.13; 95% CI: 0.77-1.64; <i>p</i> = 0.53), but showed an inverted U-shaped curve, with maximal benefit at a 1:1 ratio (50% THC). <b><i>Conclusions:</i></b> These preliminary results offer a unique view of real-world medical cannabis use and identify several areas for future research.