Trait impulsivity prospectively predicts lower methadone treatment retention: moderation by pain catastrophizing

Background Empirical evidence supports the use of methadone as the standard of care for opioid use disorder. However, low retention in methadone treatment is one of the largest impediments to treatment success. Although several psychological and personality traits have been associated with substance use disorder, little work has studied the impact of these individual patient factors on addiction treatment outcomes such as treatment retention. Objectives To examine the association of methadone retention with trait impulsivity and pain catastrophizing. Methods We conducted exploratory analyses of data obtained from a randomized clinical trial (ClinicalTrials NCT02941809; registration date: 10/19/2016). Participants were adult treatment-seeking women and men diagnosed with moderate to severe opioid use disorder referred for methadone treatment ( N = 80; 61% male) at an opioid treatment program in Baltimore, Maryland. Scores on the Barratt Impulsivity Scale and the Pain Catastrophizing Scale were collected following treatment intake, and the total window for observation of treatment retention was 365 days. Retention in methadone treatment was treated as a dichotomous outcome (1/0) based on whether a participant had dropped out of treatment at any point in time or if they missed 30 consecutive days in a row. Results Cox regression models revealed that: (i) higher impulsivity was associated with a higher risk of dropping out of methadone treatment (i.e. lower treatment retention)[Hazard Ratio (HR) = 1.04, 95% confidence interval (CI) = 1.001–1.008, p < .05), and (ii) pain catastrophizing moderated the effect of trait impulsivity on risk of dropping out of methadone treatment, such that the effect of trait impulsivity on risk of dropping out of treatment was greatest in participants with low pain catastrophizing (HR=0.995, p < .01). These findings remained significant after controlling for age and treatment group. Conclusions These findings suggest that trait impulsivity is a significant risk factor for low methadone treatment retention, especially for persons with low pain catastrophizing. Trial registration ClinicalTrials.gov: NCT02941809 (registration date: 10/19/2016).