Five-year opioid treatment study found persistent heroin use linked to crack but not cannabis escalation | Research

The takeaway

Among 7,717 patients in opioid substitution treatment over five years, continued high-level heroin use predicted high crack cocaine and alcohol use, but was actually associated with less cannabis escalation.

People interested in opioid treatment outcomes, substance use patterns, and how cannabis fits into polysubstance use.

Persistent heroin use predicted 58.7x higher crack use but 0.5x less cannabis escalation

What the researchers found

Continued high-level heroin use during OST predicted continued high-level crack cocaine use (RRR 58.7), continued high-level alcohol use (RRR 1.2), and increasing unspecified drug use (RRR 1.7), but was associated with less high-and-increasing cannabis use (RRR 0.5).

Why it matters

Understanding how different substance use patterns cluster during long-term opioid treatment helps clinicians identify which patients need additional support. The finding that cannabis use did not escalate alongside heroin non-response adds nuance to polysubstance use assumptions.

The numbers in context

7,717 patients followed for 5 years. Continued high heroin use predicted crack (RRR 58.7), alcohol (RRR 1.2), but less cannabis escalation (RRR 0.5). Increasing crack use reduced odds of successful treatment completion (AOR 0.2-0.5).

How the study worked

Prospective observational cohort of 7,717 adults continuously enrolled in opioid substitution treatment with methadone or buprenorphine from 2008/09 to 2013/14 in England. Multi-level latent class growth analysis identified substance use trajectories across 11 six-monthly clinical reviews.

What this study cannot tell us

Observational design cannot determine causation. Cannabis and other drug use were clinician-assessed, not biochemically verified at every timepoint. English treatment population may not generalize to other healthcare systems.

How to read the evidence

Strong: large national prospective cohort with five years of follow-up and sophisticated trajectory modeling.

When this study was published

Published in 2019, using 2008-2014 data.

The bigger picture

Crack cocaine, not cannabis, was the substance most tightly linked to persistent heroin use and treatment failure. This suggests that crack cocaine co-use should be a primary clinical concern in long-term opioid substitution programs.

Questions still open

Why was cannabis use inversely associated with persistent heroin use? Are patients who use cannabis during OST substituting it for heroin, or do they represent a fundamentally different patient population?

Common questions

Does cannabis use worsen outcomes in opioid treatment?

This study found cannabis use was not associated with treatment failure. In fact, continued high-level heroin use predicted less cannabis escalation. Crack cocaine, not cannabis, was the substance most linked to poor outcomes.

What predicts failure in long-term opioid treatment?

Increasing crack cocaine use was the strongest predictor of not completing treatment successfully. Continued high-level heroin use also predicted higher alcohol and other drug use.

Read the original research

Change in alcohol and other drug use during five years of continuous opioid substitution treatment.

Drug and alcohol dependence, 194, 438-446

View on PubMed ↗Publisher’s paper ↗

Citation

Eastwood, Brian; Strang, John; Marsden, John. (2019). Change in alcohol and other drug use during five years of continuous opioid substitution treatment.. Drug and alcohol dependence, 194, 438-446. https://doi.org/10.1016/j.drugalcdep.2018.11.008