Among 1.3 million VA patients on opioids for pain, more opioid prescriptions were associated with higher rates of cannabis use disorder | Research

The takeaway

In a national sample of over 1.3 million veterans receiving opioids for non-cancer pain, more opioid prescriptions were associated with greater likelihood of having a cannabis use disorder.

Read this if you use both opioid medications and cannabis for pain management.

1.3 million patients: more opioid fills = more cannabis use disorder

What the researchers found

Researchers examined cannabis use disorder (CUD) rates among 1,316,464 VHA patients with non-cancer pain who received opioid medications. Using logistic regression controlling for confounders, they found that greater numbers of opioid prescription fills were associated with greater likelihood of having a CUD diagnosis.

The relationship held across prescription fill categories (0, 1-2, 3-10, 11-19, 20+), though it was somewhat reduced for those receiving the most prescriptions (20+) after controlling for confounders like other substance use disorders and psychotropic medications.

The authors concluded that cannabis and opioids appear to function as complements (associated with increased use of both) rather than substitutes (where more of one means less of the other), warranting increased clinical attention to cannabis use in patients receiving opioid prescriptions.

Why it matters

The substitution hypothesis (that cannabis could replace opioids and reduce the overdose epidemic) is a major policy argument. This study provides contrary evidence: in practice, cannabis and opioid use appear to go together rather than substitute for each other.

The numbers in context

1,316,464 VHA patients analyzed. More opioid fills associated with more CUD. Relationship held across fill categories: 0, 1-2, 3-10, 11-19, 20+. Slightly attenuated at 20+ fills after adjustment.

How the study worked

Cross-sectional analysis of 1,316,464 VHA patients with non-cancer pain diagnoses receiving opioid medications in fiscal year 2012. Bivariate and logistic regression analyses examined the relationship between number of opioid prescription fills and CUD diagnosis.

What this study cannot tell us

Cross-sectional design cannot determine temporal direction. VHA patient population (predominantly male, older, with high comorbidity) may not generalize. CUD diagnosis may be underreported. Cannot determine whether patients used cannabis to manage pain or for other reasons.

How to read the evidence

Large national cross-sectional analysis with statistical controls, but cannot establish causal direction.

When this study was published

Published in 2015 using fiscal year 2012 VHA data.

The bigger picture

The cannabis-opioid substitution debate has major policy implications. This large-scale observational study suggests that in a real-world clinical population, the relationship is complementary rather than substitutive, though the study design cannot determine causation.

Questions still open

Do patients use cannabis to manage pain that opioids inadequately control? Would controlled cannabis access reduce opioid prescriptions, or would it add another substance to the mix? Does the complementary pattern hold in non-veteran populations?

Common questions

Does cannabis replace opioids for pain?

This large VA study found the opposite pattern: patients with more opioid prescriptions were more likely to also have cannabis use disorder, suggesting the two substances complement rather than substitute for each other.

Should doctors screen for cannabis use in opioid patients?

The authors recommended increased attention to cannabis use disorders among patients receiving numerous opioid prescriptions, as the two substances appeared to be used together rather than one replacing the other.

Read the original research

Concomitant cannabis abuse/dependence in patients treated with opioids for non-cancer pain.

The American journal on addictions, 24(6), 538-45

View on PubMed ↗Publisher’s paper ↗

Citation

Hefner, Kathryn; Sofuoglu, Mehmet; Rosenheck, Robert. (2015). Concomitant cannabis abuse/dependence in patients treated with opioids for non-cancer pain.. The American journal on addictions, 24(6), 538-45. https://doi.org/10.1111/ajad.12260