Missing Visits Counted as Cocaine Relapse in the CBD Trial
The cocaine-use-disorder trial treated missing outcome data as relapse and missing urine tests as positive. Those were analysis rules, not laboratory detections in specimens that were never collected.
The protocol combined reports and urine testing
Participants received CBD or placebo during inpatient detoxification and subsequent outpatient follow-up. Time to first cocaine use was assessed using reported use and weekly urine testing. For the cocaine-use percentage, the protocol considered missing urine tests positive. Missing relapse information was handled conservatively as relapse.
Assumption and observation need separate labels
A measured positive test and an imputed positive can contribute to the same summary while representing different evidence. The rule may reduce an overly optimistic estimate of abstinence, but it does not identify why a visit was missed. Nor does the rule alone establish the direction or magnitude of bias in the CBD-placebo comparison.
Retain the randomized result
CBD did not demonstrate superiority on the primary craving or relapse outcomes under this protocol. That result should not be replaced with an imagined benefit among missing participants. A careful appraisal reports the missing-data rule, attrition and measured evidence together. It also avoids saying that every counted relapse was independently confirmed by a positive biological specimen.
Related analysis: the cocaine-craving and relapse findings.
Research cited
Mongeau-Pérusse and colleagues (2021). Cannabidiol as a treatment for craving and relapse in individuals with cocaine use disorder: a randomized placebo-controlled trial. DOI: 10.1111/add.15417.
