Treatment Patterns and Patient Characteristics in Misdiagnosis of Bipolar I Disorder

Abstract

Background: Bipolar I disorder (BP-I) presents significant diagnostic challenges, often misdiagnosed as major depressive disorder (MDD) during initial evaluation. Misdiagnosis can lead to inappropriate treatment regimens, including the prescription of antidepressant monotherapy, which poses the risk of inducing manic episodes in BP-I patients. Understanding post-misdiagnosis treatment patterns among BP-I patients is necessary to improve diagnostic accuracy and treatment selection. Objective: This retrospective cohort study aimed to characterize treatment patterns among the BP-1 patients who misdiagnosed with MDD during their misdiagnosis period and assess their associations with the time until correct BP-I diagnosis. Methods: Utilizing the MarketScan database, we identified two cohorts: BP-I patients with the history of misdiagnosis with MDD, and BP-I patients without the history of MDD misdiagnosis. In the misdiagnosed group, we described the first and last treatment regimens during the misdiagnosis period. We performed multinomial logistic regression to investigate the associations between patients and provider characteristics and the first treatment regimen after misdiagnosis. We employed Cox Proportional Hazard Model to assess the associations between treatment patterns and time until BP-I diagnosis. We compared the first treatment regimen after BP-I diagnosis between the two groups. Results: Among 21,771 misdiagnosed BP-I patients, 28.5% received antidepressant monotherapy initially, with 18.8% continuing this regimen before BP-I diagnosis. Conversely, 13.3% persisted with antidepressant monotherapy post-BP-I diagnosis. In the non-misdiagnosed BP-I cohort, 11.2% initiated antidepressant monotherapy. Notably, mood stabilizer/anticonvulsant monotherapy post-misdiagnosis had the highest hazard of BP-I diagnosis compared to antidepressant monotherapy (HR: 1.26, 95% CI: 1.19-1.34, p<0.001). Conclusion: Our findings highlight disparities in initial diagnoses between acute care providers, internal medicine, and family practice versus mental health facilities, psychiatrists, and nurse practitioners. This may reflect differences in diagnostic expertise and referral patterns. Notably, prevalent use of antidepressants and anxiolytics contravenes current guidelines, underscoring the need for improved clinical practice. The lack of screening tools for BP-I compared to MDD emphasizes the necessity for more comprehensive assessment tools to improve diagnostic accuracy.