Validity of PDQ4+ self-screening to assess the impact of personality disorder traits on the course of bipolar disorder

•A higher number of maladaptive personality traits, was associated with an unfavorable course of bipolar disorder.•Patients with a positive screening on particular personality disorder were on average rated as more severely ill.•The sum of all dysfunctional personality traits had a higher validity than the individual personality disorders.•Treatment planning could be adapted for patients with a high number of maladaptive personality traits.