Reduced Stimulant Use Outcomes May Reveal Treatment Effects Missed by Abstinence Measures
Key Clinical Summary:
- A meta-analysis of 12 randomized controlled trials found no pharmacotherapy significantly improved stimulant abstinence compared with placebo among patients with cocaine or methamphetamine use disorder.
- Reduced stimulant use, defined as a shift from high-frequency to low-frequency use or abstinence, produced larger treatment effect estimates than abstinence alone, although pooled effects remained nonsignificant.
- Cabergoline demonstrated a significant positive signal for reduced cocaine use in medication-specific analyses, suggesting that outcomes beyond abstinence may reveal clinically relevant treatment effects.
Stimulant use disorders, including cocaine and methamphetamine dependence, remain major public health challenges without approved pharmacologic treatments. In a meta-analysis published in JAMA Psychiatry, investigators found that no pharmacotherapy significantly improved stimulant abstinence compared with placebo. Evaluating reduced stimulant use rather than relying exclusively on complete abstinence outcomes, though, could provide additional insight into treatment efficacy.
Study Findings
Researchers conducted a one-stage individual participant meta-analysis of 12 double-blind randomized controlled trials performed between 2001 and 2011. The studies evaluated topiramate, bupropion, modafinil, ondansetron, tiagabine, cabergoline, reserpine, selegiline, and baclofen against placebo in individuals seeking treatment for cocaine or methamphetamine dependence. All participants also received cognitive behavioral therapy (CBT).
The analysis included 2000 participants, comprising 1134 individuals enrolled in cocaine-use trials and 866 in methamphetamine-use trials.
The primary endpoint was reduced stimulant use, defined as a transition from high-frequency use (5 or more days per month) to low-frequency use (1-4 days per month) or complete abstinence based on self-report. Abstinence, confirmed by urine toxicology testing, served as the secondary endpoint.
At the end of treatment, a weighted 31.2% of participants achieved reduced use, compared with 13.3% who achieved abstinence. However, pooled analyses showed no statistically significant differences between active pharmacotherapy and placebo for either reduced use or abstinence, both overall and when stratified by stimulant type.
In medication-specific analyses, cabergoline was associated with significantly higher rates of reduced cocaine use compared with pooled placebo, with a Cohen h effect size of 0.352 (95% CI, 0.115-0.590).
Clinical Implications
The findings suggest that exclusive reliance on abstinence as a trial endpoint may underestimate potentially meaningful treatment effects in stimulant use disorder research. Complete abstinence is often difficult to achieve, particularly in chronic substance use disorders, and may represent a stringent benchmark that fails to capture clinically important improvements.
Reduced stimulant use has been associated with better health outcomes and may provide a more sensitive measure of therapeutic benefit. In this analysis, effect size estimates for reduced use were consistently larger than those observed for abstinence, despite not reaching statistical significance in pooled analyses.
For clinicians, these results support consideration of a continuum of treatment outcomes when evaluating pharmacotherapies for stimulant use disorder. Measuring reductions in frequency of use alongside abstinence may offer a more comprehensive assessment of patient response and help identify promising therapeutic signals that warrant further investigation.
Expert Commentary
“The observed patterns suggest that moving beyond an abstinence-only framework toward one that recognizes reductions in use as an additional treatment outcome could help identify clinically relevant pharmacologic signals worthy of further investigation,” wrote Masoumeh Amin-Esmaeili, MD, MPH, Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, and study coauthors.
“In the real world, recognizing reduction in drug use as meaningful progress provides a more realistic and patient-centered approach for evaluating the outcome of addiction treatment,” they concluded.
