Abstract
Inclusion of concerned significant others (SOs) in alcohol use treatment has demonstrated efficacy but has not been tested in the context of brief interventions. In this study, individual motivational interviewing (MI) sessions were compared with MI sessions including a significant other on within-treatment outcomes (alliance, fidelity, client satisfaction, and engagement). Participants (N = 382) were adult alcohol users recruited in a Level I trauma center. Perceived alliance did not differ across conditions, but patients and SOs reported higher alliance, satisfaction, and engagement than was perceived by the therapist. The occurrence of MI components, or discussion areas, was consistent across conditions. Higher baseline SO drinking was associated with lower patient engagement, whereas higher baseline SO acceptance of patient drinking was associated with lower SO engagement. Results suggest that individual MI sessions can be adapted to include an SO with minimal impact on patient acceptability and treatment fidelity. Research should, however, consider SOs' influence on participant outcomes and the relevance of specific SO characteristics.