Measurement of insight in patients with bipolar disorder: are self-rated scales developed for patients with schizophrenia applicable?

Our aim was to study if the Birchwood Insight Scale has acceptable psychometric properties when used for patients with bipolar disorders. Patients with schizophrenia (n = 101), bipolar I (n = 57), and bipolar II disorder (n = 37) completed the self-report scale. The items form 3 subscales, awareness of illness, relabeling of symptoms, and need for treatment. The total scale had good internal consistency for patients with schizophrenia, fairly good for bipolar I, but poor for bipolar II disorder. On subscale level the internal consistency was mostly marginal to poor for all patient groups. The level of insight was similar in schizophrenia and bipolar I disorder. The psychometric properties for the insight scale were poorer in bipolar disorders than in schizophrenia, and the scale did not work for patients with bipolar II disorder. This suggests a cautious use of the scale across different diagnostic groups.