Effectiveness of olanzapine in the treatment of anorexia nervosa: A systematic review and meta-analysis

Objective Anorexia nervosa (AN) is a severe psychiatric disorder characterized by starvation and malnutrition, a high incidence of coexisting psychiatric conditions, and treatment resistance. The effect of pharmacotherapy has been controversial. Method A systematic review was conducted for evidence of an effect of olanzapine versus placebo in adults or its effect as adjuvant treatment of AN in adolescents. Results A total of seven articles (304 patients with AN) were identified. There were four double-blind, randomized studies examining the effect of olanzapine in the treatment of AN. The mean difference in body mass index (BMI) at the end of treatment between olanzapine and placebo was 0.67 kg/m(2) (95% confidence interval (CI) 0.15-1.18 kg/m(2); p = 0.01; I-2 = 0%, p for heterogeneity < 0.79). The olanzapine groups showed a significant increase in BMI of 0.68 kg/m(2) (95% CI 0.22-1.13 kg/m(2); p I-2 = 0%, p for heterogeneity = 0.74) compared to the placebo groups. Only two studies examined the effect of olanzapine as adjuvant treatment in adolescents and showed an increase in BMI of 0.66 kg/m(2) (95% CI -0.36 to 1.67 kg/m(2); p = 0.21; I-2 = 11%, p for heterogeneity = 0.32). Discussion Olanzapine showed efficacy in the treatment of AN with an increased BMI at the end of treatment in adults. The effect of olanzapine as adjuvant treatment in adolescents remains unclear.