A trial’s randomized denominator and its analyzed denominator are not always the same. Reading the participant flow can change the interpretation of an apparently complete follow-up result.
The numbers behind the abstract
Ahmadi and colleagues’ 2019 report compared methamphetamine-withdrawal craving during 14 inpatient days. The full results describe 69 randomized men: 35 assigned buprenorphine and 34 bupropion. Four bupropion-assigned patients refused medication initially, leaving 35 and 30 treated participants; all 65 completed follow-up.
Day-one doses were sublingual buprenorphine 4 mg or oral bupropion 150 mg. Days 2–14 used 8 mg/day or 300 mg/day, respectively, divided twice daily. Daily craving ratings used a 0–10 scale. The reported group effect favored buprenorphine (p=0.011), while the group-by-day interaction was nonsignificant. No placebo or untreated group was included.
Completion among starters is not completion among everyone randomized
Describing the study simply as 65 randomized participants with 100% completion would omit the four post-assignment refusals. Completion of follow-up among those who began treatment answers a different question from retention of every randomized participant.
This matters because removing people after assignment can compromise the original group comparison. The direction and size of any resulting bias cannot be established merely from the fact that no further participants dropped out. A transparent explanation preserves both the randomized and treated counts.
What does a comparison without placebo establish?
The two active regimens can be compared within the study’s design and analytical limitations. Declining craving in both groups, however, cannot establish that both medicines caused the decline. Time, inpatient abstinence and other features of the setting provide alternative explanations that the shared before-and-after pattern cannot separate.
The nonsignificant group-by-day interaction also should remain visible. A group-level difference and a demonstrated difference in the trajectory over time are different statistical statements. Calling one a progressively increasing treatment advantage would require evidence directed at that trajectory.
Why this was not a relapse-prevention trial
The observation period concerned withdrawal craving in a controlled inpatient environment. It did not establish what happened after discharge or whether either regimen prevented return to use in the community. A recommendation about long-term relapse prevention would require that outcome to be followed and compared.
The paper is therefore useful historical evidence about a short, selected active-treatment comparison. Its dosing description records what was studied; it is not an instruction to start either medication for methamphetamine craving.
Source
Ahmadi J, Sahraian A, Biuseh M. A randomized clinical trial on the effects of bupropion and buprenorphine on the reduction of methamphetamine craving. Trials. 2019;20:468. doi:10.1186/s13063-019-3554-6. Publisher full text.