Real-World Effectiveness of Clozapine for Borderline Personality Disorder: Results From a 2-Year Mirror-Image Study.

While some second-generation antipsychotics have shown efficacy on patients with borderline personality disorder (BPD), limited data exist regarding the effect of clozapine. Thus, we aimed to investigate the effects of clozapine on naturalistic outcomes in BPD patients with a 2-year mirror-image model. Among 25,916 patients with BPD, 1,107 redeemed ≥ 1 clozapine prescription. Of these, 18,188 were "specific" BPD patients, and 102 redeemed ≥ 1 clozapine prescription. During a mean observation period of 598.51 days, in all BPD patients, clozapine was associated with a significant reduction in psychiatric admissions from 2.52 (95% CI [2.31, 2.78]) to 2.00 (95% CI [1.77, 2.23]) admissions (p < .001) and a significant reduction in psychiatric bed-days from 190.08 (95% CI [176.84, 203.33]) to 65.95 (95% CI [58.27, 73.66]) bed-days (p < .001). Similar findings were found for "specific" BPD patients. The number of patients with intentional self-harm or overdose decreased significantly from 189 to 114 individuals (p < .001) after clozapine initiation. Randomized trials evaluating the risk- benefit ratio of clozapine in patients with severe BPD are warranted.