Aim: To evaluate the association between coping self-efficacy and persistent use of heroin by patients enrolled in a methadone treatment program.

Design and methods: Cross-sectional survey. One hundred and ninety-one patients attending outpatient methadone clinics in South-East England, United Kingdom. Validated questionnaires were used to assess drug use (Maudsley Addiction Profile), alcohol use (Alcohol Use Disorders Identification Test), mental health (Hospital Anxiety and Depression Scale) and coping self-efficacy (brief 8-item Drug Taking Confidence Questionnaire).

Results: Half of the participants (95/191) reported heroin use in the preceding 14-day period. Heroin use during methadone treatment was associated with financial problems (P = 0.008), spending time with other drug users (P < 0.001), cocaine use (P = 0.002), low mood (P = 0.002) and dissatisfaction with the daily methadone dose (P = 0.014). Compared with 'Heroin-abstinent' patients, the 'Heroin' group reported significantly lower mean coping self-efficacy scores (t = 9.8, d.f. = 182, P < 0.001, effect size 1.17). After correcting for the effects of co-variants in a logistic regression model, the main determinants of persistent heroin use were 'coping self-efficacy' [B -0.05; standard error (SE) 0.008; Wald 36.6; odds ratio (OR) 0.95, 95% confidence interval (CI) 0.94, 0.97; P < 0.001] and 'dissatisfaction with methadone dose' (B 0.93; SE 0.46; Wald 4.1; OR 2.5, 95% CI 1.03, 6.25; P = 0.042). Satisfaction with methadone dose showed no association with self-efficacy. DISCUSSION AND CONCLUSIONS; While heroin use during methadone treatment can partly be explained by inadequate dosing, our data suggest a more complex picture with significant contribution from poor coping self-efficacy. Efforts aimed at enhancing and maintaining the patients' self-efficacy and social skills are likely to improve heroin and other drug use outcomes with added benefits for treatment completion rates and the throughput of methadone programs.