Diagnostic depressive symptoms of the mixed bipolar episode

Background, There is not yet consensus on the best diagnostic definition of mixed bipolar episodes. Many have suggested the DSM-III-R/-IV definition i s too rigid. We propose alternative criteria using data from a large patien t cohort. Methods. We evaluated 237 manic in-patients using DSM-III-R criteria and th e Scale for Manic States (SMS). A bimodally distributed factor of dysphoric mood has been reported from the SMS data. We used both the factor and the DSM-III-R classifications to identify candidate depressive symptoms and the n developed three candidate depressive symptom sets. Using ROC analysis we determined the optimal threshold number of symptoms in each set and compare d the three ROC solutions. The optimal solution was tested against the DSM- III-R classification for cross-validation. Results. The optimal ROC solution was a set, derived from both the DSM-III- R and the SMS, and the optimal threshold for diagnosis was two or more symp toms. Applying this set iteratively to the DSM-III-R classification produce d the identical ROC solution. The prevalence of mixed episodes in the cohor t was 13.9 % by DSM-III-R, 20.2 % by the dysphoria factor and 27.4 % by the new ROC solution. Conclusions. A diagnostic set of six dysphoric symptoms (depressed mood, an hedonia, guilt, suicide, fatigue and anxiety), with a threshold of two symp toms, is proposed for a mixed episode. This new definition has a foundation in clinical data, in the proved diagnostic performance of the qualifying s ymptoms, and in ROC validation against two previous definitions that each h ave face validity.