RESUMEN
A nonblinded randomized trial was conducted at two Canadian provincial outpatient addiction clinics that tested the effectiveness of a systemic congruence couple therapy (CCT) versus individual-based treatment-as-usual (TAU) on nine clinical outcomes: (1) primary outcomes-alcohol use and gambling, psychiatric symptoms, and couple adjustment; (2) secondary outcomes-emotion regulation, substance use, depression, post-traumatic stress symptoms, and life stress. Data of primary clients and partners (N = 46) were analyzed longitudinally across baseline, posttreatment (5 months), and follow-up (8 months). Alcohol use disorder (95%) and gambling disorder (5%) were in the severe range at baseline, and co-addiction was 27%. Psychiatric comorbidity was 100%, and 18% of couples were jointly addicted. Between-group comparison favored CCT in primary outcomes with medium-to-large effect sizes (Cohen's h = 0.74-1.44). Secondary outcomes were also significantly stronger for CCT (Cohen's h = 0.27-1.53). Within-group, for all primary outcomes, a significant proportion of symptomatic CCT clients and partners improved, converging with ANOVA results of large effect sizes (0.14-0.29). All secondary outcomes improved significantly in CCT with large effect sizes (0.14-0.50). TAU showed significant within-group improvement in alcohol use, other substance use, and life stress with large effect sizes (0.16-0.40). Primary clients and partners made largely equivalent improvement within CCT and within TAU. Results were triangulated with clients' satisfaction ratings and counselors' reports. Overall, significant within-group effects were detected for CCT both clinically and statistically and between-group difference favored CCT. Future trials are required to validate these promising findings.