The Efficacy of Skills for Improving Distress Intolerance in Substance Users: A Randomized Clinical Trial

Abstract

Background: Following inpatient treatment for substance use disorders, abstinence remains elusive. Distress tolerance (DT), persistence in goal directed activity despite psychological distress, is implicated in addictions treatment outcomes. A novel, targeted treatment, Skills for Improving Distress Intolerance (SIDI), integrates skills training with emotional exposure and shows short-term efficacy and specificity to improve distress tolerance. We aimed to compare SIDI to supportive counseling (SC) in DT post-treatment as well as DT and percentage of days using (drugs or alcohol) over 6-month follow-up in the community. Methods: Individuals who attended an inpatient addictions treatment were randomized to 10 weekly group sessions of SIDI or SC, assessed post-treatment, and monitored for six months following community reintegration. Primary outcomes included DT and proportion days using substances (PDU). Variables were assessed at baseline, immediately after SIDI or SC protocol completion, and at 1-, 3-, and 6-months post-discharge. Instruments included three self-reported measures of distress tolerance and the timeline follow-back of substance-using days. Findings: Compared to SC, participants assigned to SIDI reported significantly greater improvement during treatment and post-discharge on several DT measures. Court-mandate status moderated the effects of intervention on drug use outcomes: among those voluntarily admitted to the inpatient treatment, SIDI reduced PDU relative to SC. Among court-mandated individuals, the effects of SIDI and SC on PDU did not differ. Change in DT during treatment predicted frequency of drug use during community reintegration. Interpretation: For individuals who receive inpatient treatment for substance use disorders, SIDI, compared to SC, produced significantly greater improvement in DT. SIDI also reduced relapse risk, but only among voluntary admissions. Change in DT predicted level of PDU in during community reintegration. Results suggest that SIDI leads to a targeted change in DT and substance use, which is sustained. Results also support DT as a key mechanism in substance use disorders. Trial Registration: clinicaltrials.gov Identifier: NCT01741415. Funding Statement: The work was supported by grants DA032582 (NIDA) and MH20030 (NIMH). Declaration of Interests: We declare no competing interests. Ethics Approval Statement: Data for this project were collected at the University of South Florida, with approval from the university’s IRB (Pro00009634). Eligible individuals provided written informed consent.