Background: This study explores factors that can influence other psychotic diagnoses in the first episode of a DSM-III-R bipolar disorder.
Methods: It includes all 163 bipolar in-patients and out-patients in the state of Alava, North of Spain (Basque country) from February 1994 to May 1996. Patients were divided into two non-overlapping groups: unstable diagnoses, bipolars with an initial diagnosis of schizophrenia (or other psychosis), and stable diagnoses of bipolar disorder.
Results: A logistic regression analysis using marital status, age at onset and mood incongruent psychotic symptoms found that the latter was the only independent factor significantly associated with an unstable diagnosis.