Ten-year diagnostic consistency of bipolar disorder in a first-admission sample

A number of reports have examined the stability of the diagnosis of schizophrenia, but fewer studies have considered the long-term consistency of a bipolar diagnosis or factors that influence the likelihood of a diagnostic change. The present study sought to estimate how consistently a bipolar diagnosis was made across a 10-year period and factors associated with consistency, particularly demographic and clinical characteristics, childhood-related factors, and illness course.

The sample included 195 first-admission patients presenting with psychosis who were assessed soon after hospitalization and at 6-month, 2-year, and 10-year follow-up and diagnosed with bipolar disorder on at least one of these assessments. Diagnoses were made using best-estimate procedures and were blind to all previous consensus diagnoses. Respondents who were consistently diagnosed with bipolar disorder were compared to those whose diagnosis shifted across assessments.

Overall, 50.3% (n = 98) of the 195 respondents were diagnosed with bipolar disorder at every available assessment, but 49.7% (n = 97) had a diagnostic shift to a non-bipolar disorder at least once over the course of the 10-year study. Childhood psychopathology and poorer illness course were among the few variables associated with increased odds of a change in diagnosis.

Even with optimal assessment practices, misdiagnosis of bipolar disorder is common, with complex clinical presentations often making it difficult to consistently diagnose the disorder over the long term.