Background: The under-recognition of hypomanic symptoms by both clinicians and patients is a major clinical problem which contributes to misdiagnosis and diagnostic delay in patients with bipolar disorder. The recent development of validated screening instruments for hypomania, such as the Hypomania Checklist (HCL-32), may help to improve the detection of bipolar disorder. In this study, we assess whether it is possible to reduce the number of items on the HCL-32 without any loss in the screening tool's ability to reliably differentiate between bipolar disorder (BD) and major depressive disorder (MDD).
Methods: Using our large samples of patients with DSM-IV defined bipolar I disorder (BD-I) (n=230) and recurrent MDD (n=322), we performed item correlations in order to identify potentially redundant items in the HCL-32. We then tested the performance of a shortened 16-item HCL questionnaire within a separate sample of patients with BD (including BD-I, BD-II and BD-NOS) (n=59) and MDD (n=76).
Results: The structure of the 16-item HCL demonstrated two main factors similar to those identified for the HCL-32 (an 'active-elated' factor and a 'risk-taking/irritable' factor). A score of 8 or more on a shortened 16-item version of the HCL had excellent ability to distinguish between BD and MDD. The sensitivity (83%) and specificity (71%) of the 16-item version were very similar to those for the full 32-item HCL.
Limitations: The HCL-16 was derived after subjects had completed the full HCL-32. It will be important to test the validity of a 'stand-alone' 16-item HCL questionnaire.
Conclusions: A shortened 16-item HCL (the HCL-16) is potentially a useful screening tool for hypomania within busy clinical settings.
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