Denmark's medical cannabis pilot showed both potential benefits and potential harms | Research

The takeaway

In Denmark's medical cannabis pilot program, users were more satisfied with treatment and had lower depression scores than matched controls, but reported higher pain levels and possible worsening of MS symptoms.

Health policymakers, medical cannabis program administrators, and clinicians prescribing within pilot programs.

Better satisfaction and lower depression, but paradoxically higher pain scores

What the researchers found

Medical cannabis users scored higher on treatment satisfaction (29.2 vs. 26.5, p=0.006) and lower on depression (3.3 vs. 4.6, p=0.03) compared to propensity-matched controls. However, users reported higher pain levels on the SF-36 bodily pain subdomain (36.3 vs. 48.7, p=0.01, lower = more pain). There were indications of worse MS symptoms in cannabis users. Side effects were generally mild.

Why it matters

Denmark's pilot program provides a rare national-level experiment in medical cannabis. The mixed results (better satisfaction and depression, worse pain scores) illustrate the complexity of evaluating medical cannabis and the danger of focusing on only positive or only negative outcomes.

The numbers in context

Treatment satisfaction: 29.2 vs. 26.5 (p=0.006). Depression: 3.3 vs. 4.6 (p=0.03). SF-36 bodily pain: 36.3 vs. 48.7 (p=0.01, lower=more pain). MS symptom indications of worsening in cannabis group. Side effects generally mild.

How the study worked

Cross-sectional study within Denmark's medical cannabis pilot program (launched January 2018). Cases who redeemed MC/CBM prescriptions were propensity-score matched to controls with same indications. Both groups completed online surveys and in-person interviews assessing depression, anxiety, cognition, satisfaction, and pain.

What this study cannot tell us

Cross-sectional design cannot determine causation. Propensity matching cannot eliminate all confounders. Self-selection into the pilot program introduces bias. Higher pain in the cannabis group may reflect worse baseline conditions.

How to read the evidence

Propensity-matched design within a national program. Limited by cross-sectional nature and potential confounding by indication.

When this study was published

2021 study from Denmark's medical cannabis pilot program (launched 2018).

The bigger picture

The paradox of higher satisfaction but worse pain scores could mean that medical cannabis improves aspects of well-being (mood, coping) without necessarily reducing pain itself. Alternatively, the higher pain scores may reflect confounding by indication: patients with worse pain may be more likely to seek cannabis treatment.

Questions still open

Why are cannabis users more satisfied despite reporting more pain? Does cannabis improve quality of life through mood rather than direct pain relief? Would randomized trials resolve the contradictory findings?

Common questions

Did medical cannabis reduce pain in Denmark's program?

Paradoxically, cannabis users reported higher pain levels than matched controls. This may reflect that people with worse pain were more likely to try medical cannabis, rather than cannabis worsening pain.

Were patients satisfied with medical cannabis?

Yes. Cannabis users scored significantly higher on treatment satisfaction and lower on depression compared to matched controls receiving conventional treatment.

Read the original research

Medical cannabis and cannabis-based medicine show both potential efficacy and potential harms: Cross-sectional comparison with controls on self-rated and interviewer-rated outcomes within the Danish pilot program on medical cannabis.

Complementary therapies in clinical practice, 45, 101476

View on PubMed ↗Publisher’s paper ↗

Citation

Kudahl, Benedikte; Berg, Marie Eva; Posselt, Christine Merrild; Nordentoft, Merete; Hjorthøj, Carsten. (2021). Medical cannabis and cannabis-based medicine show both potential efficacy and potential harms: Cross-sectional comparison with controls on self-rated and interviewer-rated outcomes within the Danish pilot program on medical cannabis.. Complementary therapies in clinical practice, 45, 101476. https://doi.org/10.1016/j.ctcp.2021.101476