Attrition in studies of substance use disorder treatment is problematic, potentially introducing bias into data analysis.

This study aimed to determine the effect of participant compensation amounts on rates of missing data and observed rates of drug use.

We performed a secondary analysis of a clinical trial of buprenorphine/naloxone among 152 treatment-seeking opioid-dependent subjects aged 15-21 during participation in a randomized trial. Subjects were randomized to a 2-week detoxification with buprenorphine/naloxone (DETOX; N = 78) or 12 weeks buprenorphine/naloxone (BUP; N = 74). Participants were compensated $5 for weekly urine drug screens and self-reported drug use information and $75 for more extensive assessments at weeks 4, 8, and 12.

Though BUP assignment decreased the likelihood of missing data, there were significantly less missing data at 4, 8, and 12 weeks than other weeks, and the effect of compensation on the probability of urine screens being positive was more pronounced in DETOX subjects.

These findings suggest that variations in the amount of compensation for completing assessments can differentially affect outcome measurements, depending on treatment group assignment.

Adequate financial compensation may minimize bias when treatment condition is associated with differential dropout and may be a cost-effective way to reduce attrition. Moreover, active users may be more likely than non-active users to drop out if compensation is inadequate, especially in control groups or in groups who are not receiving active treatment.