Miranda 2017.
| Methods | Randomised placebo‐controlled pilot study. Participants stratified on sex, cannabis dependence and baseline working memory function prior to randomisation | |
| Participants | Setting: outpatient, Providence, USA. Scheduled duration 6 weeks Participants: 66 adolescents (aged 15–24 years), used cannabis at least twice weekly in prior 28 days and experiencing some clinically significant problems Group sizes: group 1, 40; group 2, 26 Groups similar on demographics (except mean age) and baseline clinical characteristics Mean age: group 1, 20.3 years, group 2, 18.8 years 48.5% male 80% met DSM‐IV‐TR criteria for cannabis abuse or dependence Exclusion criteria: significant psychiatric conditions. |
|
| Interventions | Group 1: topiramate, titrated over 4‐weeks then stabilised at 200 mg/day for 2 weeks Group 2: placebo MET biweekly for 3 sessions |
|
| Outcomes | Number completing study, days in treatment, sessions of MET attended Cannabis use (grams per use day and % days with use) Medication compliance Adverse effects |
|
| Notes | Funding: research grant (NIDA) 1 author declared associations with pharmaceutical companies. |
|
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Quote: "An investigator with no direct participant contact used a computer‐generated random allocation sequence to assign participants to treatment conditions on a 2:1 (topiramate to placebo) ratio." |
| Allocation concealment (selection bias) | Low risk | Quote: "An investigator with no direct participant contact used a computer‐generated random allocation sequence to assign participants to treatment conditions." "An independent compounding pharmacy provided topiramate and placebo capsules, which were identical in appearance. Capsules were prepackaged in 7‐day blister packaging cards consecutively numbered according to a computer‐generated randomization schedule to ensure that the researchers who enrolled and assessed participants were blind to treatment assignments." |
| Blinding of participants and personnel (performance bias) All outcomes | Low risk | Quote: "An independent compounding pharmacy provided topiramate and placebo capsules, which were identical in appearance;" "Participants and study personnel in direct contact with participants were blind to treatment assignments." "Counselors were blind to participants' medication condition and did not conduct any research assessments with participants." |
| Blinding of outcome assessment (detection bias) All outcomes | Low risk | Quote: "An independent compounding pharmacy provided topiramate and placebo capsules, which were identical in appearance;" "Participants and study personnel in direct contact with participants were blind to treatment assignments." |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Quote: "Of the 66 participants, 39 youth (59.1 percent) completed the trial. As expected, attrition occurred disproportionally in the topiramate condition (52.5 percent) compared with the placebo condition (23.1 percent)." Comment: attrition is an outcome for this review. Missing data were imputed in analyses of cannabis use outcomes. |
| Selective reporting (reporting bias) | Low risk | None apparent |
| Other bias | Low risk | None apparent |