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

Objectives: 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. Methods: 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. Results: 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. Conclusions: 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.