Background: Approximately 70% of patients with bipolar disorder (BPD) are initially misdiagnosed, resulting in significantly delayed diagnosis of BPD (7-10 years on average). Misdiagnosis and diagnostic delay adversely affect health outcomes and lead to the use of inappropriate treatments. As depressive episodes/symptoms are the predominant presentation of BPD, misdiagnosis as major depressive disorder (MDD) is common. Self-rated screening instruments for BPD exist but their length and underemphasis on BPD diagnostic validators are barriers to implementation, especially in primary care settings where many of these patients initially present. We developed a brief, pragmatic bipolar I disorder (BPD-I) screening tool that not only screens for manic symptoms but also includes risk factors for BPD-I (e.g., number of prior antidepressants, age of onset) to help clinicians reduce misdiagnosis of BPD-I as MDD.
Methods: Existing questionnaires and risk factors were identified through a targeted literature search; a diverse panel of experts was enlisted to select concepts thought to differentiate BPD-I from MDD. Individuals with self-reported BPD-I or MDD participated in iterative sets of cognitive debriefing interviews (N=12) to test and refine the item-wording. A multisite, cross-sectional, observational study was conducted to evaluate the screening tool’s predictive validity. Participants with clinical interview-confirmed diagnoses of BPD-I or MDD completed a 10-item screening tool and other questionnaires. Data were analyzed to identify a subset of items and item-thresholds to optimize tool sensitivity and specificity, with the goal of providing strong psychometric properties with the fewest number of items.
Results: A total of 160 clinical interviews were conducted; 139 patients had clinical interview-confirmed BPD-I (n=67) or MDD (n=72). The screening tool was reduced from 10 to 6 items based on item-level analysis. When 4 items or more were endorsed (“yes”), the sensitivity of this tool for identifying patients with BPD-I was 0.92 and specificity was 0.78; positive and negative predictive values, based on the analysis sample, were 0.78 and 0.92, respectively. These properties represent an improvement over the Mood Disorder Questionnaire, while using >50% fewer items.
Conclusion: This new 6-item BPD-I screening tool serves to identify patients with depression who may instead have BPD-I. Use of this tool can provide real-world guidance to practitioners on whether more comprehensive assessment for BPD is warranted. Implementation of a brief and valid tool provides opportunity to improve diagnostic accuracy, appropriate treatment selection, and positive patient outcomes, especially for busy clinical practices.
