Interpersonal Outcomes of Complex Post-Traumatic Stress Disorder and Borderline Personality Disorder: A Systematic Review and Meta-Analysis.

Severe interpersonal difficulties are central to both complex posttraumatic stress disorder (CPTSD) and borderline personality disorder (BPD), two trauma-related disorders with substantial clinical overlap. Whether their relational impairments reflect shared or distinct profiles remains an open question. To address this, we conducted a systematic review and three-level meta-analysis of 92 studies (20 on CPTSD, N = 9,657; 72 on BPD, N = 17,842) reporting associations with interpersonal problems. Medium-to-large effects were observed for both CPTSD (r = .48, 95% CI [0.37, 0.58]) and BPD (r = .39, 95% CI [0.31, 0.46]). Moderator analyses suggested different correlates of impairment: in CPTSD, disturbances in self-organization symptoms showed stronger links with interpersonal problems, particularly social dysfunction, whereas in BPD, maladaptive attachment patterns exhibited the strongest associations. These findings indicate that, although both disorders involve pervasive relational difficulties, they may be underpinned by partially distinct interpersonal profiles. This study provides evidence that can assist in clarifying diagnostic boundaries between CPTSD and BPD, and in informing tailored therapeutic approaches targeting social function in CPTSD and attachment dysregulation in BPD.