The Role of Out-of-Session Skills Use in Sage, a Couple-Based Intervention: Enhancing Borderline Personality Disorder Recovery and Relationship Quality

Abstract

Borderline Personality Disorder (BPD) is characterized by emotional and interpersonal difficulties, particularly in romantic relationships. Sage is a 12-session conjoint intervention developed to improve BPD and relationship functioning by learning and practicing skills outside of therapy sessions (out-of-session skills use). This study examined whether couples (N = 21) increased out-of-session skills use across Sage and whether skills use predicted improvements in BPD and relationship outcomes. Generalized Estimating Equations revealed that individuals with BPD and romantic partners increased general skills use, while skills use during conflict decreased. Greater between-person and within-person skills use predicted improvements in BPD symptom severity, emotion dysregulation, and suicidal ideation. However, skills use did not predict most relationship outcomes, and higher between-person skills use predicted reduced relationship satisfaction in romantic partners over time. Findings highlight the importance of out- of-session skills use in conjoint BPD treatment and the potential significance of contextual and methodological factors on this relationship.