- Personality Disorders
- Objective: The authors examined whether lamotrigine is a clinically effective and cost-effective treatment for people with borderline personality disorder. Method: This was a multicenter, double-blind, placebo-controlled randomized trial. Between July 2013 and November 2016, the authors recruited 276 people age 18 or over who met diagnostic criteria for borderline personality disorder. Individuals with coexisting bipolar affective disorder or psychosis, those already taking a mood stabilizer, and women at risk of pregnancy were excluded. A web-based randomization service was used to allocate participants randomly in a 1:1 ratio to receive either an inert placebo or up to 400 mg/day of lamotrigine. The primary outcome measure was score on the Zanarini Rating Scale for Borderline Personality Disorder (ZAN-BPD) at 52 weeks. Secondary outcome measures included depressive symptoms, deliberate self-harm, social functioning, health-related quality of life, resource use and costs, side effects of treatment, and adverse events. Results: A total of 195 (70.6%) participants were followed up at 52 weeks, at which point 49 (36%) of those in the lamotrigine group and 58 (42%) of those in the placebo group were taking study medication. The mean ZAN-BPD score was 11.3 (SD=6.6) among those in the lamotrigine group and 11.5 (SD=7.7) among those in the placebo group (adjusted difference in means=0.1, 95% CI=21.8, 2.0). There was no evidence of any differences in secondary outcomes. Costs of direct care were similar in the two groups. Conclusions: The results suggest that treating people with borderline personality disorder with lamotrigine is not a clinically effective or cost-effective use of resources.