About 20% of rheumatology patients actively use cannabis, and meta-analysis shows pain improvement | Research

The takeaway

A systematic review of 10,873 rheumatology patients found about 40% had ever used cannabis and 15% currently used it, with meta-analysis showing significant pain reduction (pooled effect size -1.75) among users.

Rheumatologists, pain management specialists, fibromyalgia patients considering cannabis

68% of fibromyalgia patients had used cannabis; significant pain reduction (ES=-1.75)

What the researchers found

40.4% of rheumatology patients reported ever using cannabis and 15.3% reported current use. Use was highest in fibromyalgia (68.2%) compared to RA/lupus (26%). Cannabis use was associated with significant pain reduction (pooled effect size -1.75, 95% CI: -2.75 to -0.76). However, cannabis users were younger, more often smokers (OR 2.91), more often unemployed (OR 2.40), and had higher baseline pain.

Why it matters

Cannabis use is common among rheumatology patients and often undisclosed. Clinicians should proactively ask about cannabis use and understand the available evidence on pain effects to guide clinical conversations.

The numbers in context

10,873 patients total; 2,900 reported cannabis use (40.4%); 15.3% current users; fibromyalgia: 68.2% ever use; RA/lupus: 26%; pain reduction pooled effect size -1.75 (95% CI: -2.75, -0.76); cannabis users younger, more smokers (OR 2.91), more unemployed (OR 2.40)

How the study worked

Systematic review and meta-analysis searching databases through June 2020. Metaproportion calculated cannabis use incidence. Standardized mean differences assessed cannabis effects on pain. Inverse-variance method used for pooling.

What this study cannot tell us

Heterogeneous study designs and cannabis products. Observational data cannot establish causation for pain reduction. Cannabis users had higher baseline pain, introducing confounding. Self-reported outcomes. Small number of studies for some analyses.

How to read the evidence

Systematic review with meta-analysis providing pooled estimates, though limited by heterogeneous observational data.

When this study was published

Published in 2021 reviewing evidence through June 2020.

The bigger picture

The high prevalence of cannabis use among rheumatology patients, especially fibromyalgia (68%), combined with the significant pain reduction signal, suggests cannabis is already a de facto part of many patients' pain management, whether or not clinicians are aware.

Questions still open

Would standardized cannabis-based pharmaceutical products show even larger pain effects than self-directed cannabis use? Should rheumatologists routinely screen for and discuss cannabis use?

Common questions

How common is cannabis use among rheumatology patients?

Very common. About 40% had ever used cannabis and 15% were currently using it. Rates were highest among fibromyalgia patients (68%) compared to those with RA or lupus (26%).

Does cannabis help with rheumatic pain?

The meta-analysis found a significant pain reduction among cannabis users (effect size -1.75). However, this is observational data, and cannabis users had higher baseline pain, so the reduction may partly reflect regression to the mean or self-selection.

Read the original research

Cannabis use assessment and its impact on pain in rheumatologic diseases: a systematic review and meta-analysis.

Rheumatology (Oxford, England), 60(2), 549-556

View on PubMed ↗Publisher’s paper ↗

Citation

Guillouard, M; Authier, N; Pereira, B; Soubrier, M; Mathieu, S. (2021). Cannabis use assessment and its impact on pain in rheumatologic diseases: a systematic review and meta-analysis.. Rheumatology (Oxford, England), 60(2), 549-556. https://doi.org/10.1093/rheumatology/keaa534