Comorbid personality disorders in manic bipolar I disorder patients is associated with increased use of long-acting injectable antipsychotic treatment and higher rates of rehospitalization

Personality disorder comorbidity is considered a poor prognostic factor among bipolar disorder patients. However, an evidence-based pharmacological treatment for this sub-population is lacking, and only few studies investigated the impact of personality disorder on bipolar disorder-I course. Here, we studied the effect of comorbid personality disorder on the administrated psychopharmacotherapy and rehospitalization risk among manic bipolar disorder-I patients. A sample of 340 patients with bipolar disorder-I, who were hospitalized with acute manic episode between 2005 and 2013, were retrospectively followed for a mean duration of 1129 days. Drug treatment at discharge and rehospitalization rates during follow-up time were compared between bipolar disorder-I patients with (n = 55) or without (n = 285) personality disorder comorbidity. Multivariate survival analyses adjusted for covariates were conducted. During the study period, 39.4% of bipolar disorder-I patients were rehospitalized due to a mood episode. Comorbid personality disorder was significantly associated with higher rates of long-acting injectable antipsychotics administration at discharge from hospitalization (adjusted odds ratio 2.66, 95% confidence interval: 1.19-5.94, P = 0.017). Comorbid personality disorder significantly increased the adjusted risk of rehospitalization due to a mood episode (hazard ratio = 2.04, 95% confidence interval: 1.29-3.23, P = 0.002). In conclusion, comorbid personality disorder in manic bipolar disorder-I patients is associated with increased use of long-acting injectable antipsychotics and higher rates of rehospitalization.