A systematic review and meta-analysis exploring the recruitment hurdles and nonparticipation rate in noninvasive brain stimulation for addictive disorders.
Pinki Sevda, Priyanka Saha, Siddharth Sarkar et al.
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In 30 seconds
This systematic review and random-effects meta-analysis examined recruitment and nonparticipation in randomized controlled trials of noninvasive brain stimulation for substance-related and behavioral addictive disorders. It included 55 trials identified through searches of major databases. The pooled nonparticipation rate was 55.9% (95% CI: 45.9-65.8%; I 2 = 99.56%, p < 0.001). Commonly reported barriers were not meeting eligibility criteria, anxiety or low motivation, and practical difficulties such as travel or frequent sessions.
Key findings
- Across 55 randomized trials, the pooled nonparticipation rate was 55.9% (95% CI: 45.9-65.8%; I 2 = 99.56%, p < 0.001).
- Failure to meet inclusion criteria was reported as a reason for nonparticipation in over 25 studies.
- At least 15 studies reported refusal related to anxiety or lack of motivation; at least 10 reported logistical barriers such as travel or session frequency.
Why it matters
High nonparticipation can constrain recruitment and may affect how well trial participants represent people with addictive disorders in clinical settings. The reported barriers point to practical and procedural factors that trial teams may need to consider when designing studies. The substantial heterogeneity in the pooled estimate also indicates that nonparticipation varied considerably across trials.
What to keep in mind
The pooled estimate had very high heterogeneity (I 2 = 99.56%), and the review included only peer-reviewed English-language studies that reported screening and randomization counts.