Validity of the DSM-5 Mixed Features Specifier Interview.

OBJECTIVES: To examine the reliability and validity of a semi-structured interview assessing the features of the DSM-5 mixed features specifier. Our goal was to develop an instrument that could be used for both diagnostic and severity measurement purposes.

METHODS: Four hundred fifty-nine psychiatric patients in a depressive episode were interviewed by a trained diagnostic rater who administered semi-structured interviews including the DSM-5 Mixed Features Specifier Interview (DMSI). We examined the inter-rater reliability and psychometric properties of the DMSI. The patients were rated on clinician rating scales of depression, anxiety, and irritability, and measures of psychosocial functioning, suicidality, and family history of bipolar disorder.

RESULTS: The DMSI had excellent joint-interview interrater reliability. More than twice as many patients met the DSM-5 mixed features specifier criteria during the week before the assessment than for the majority of the episode (9.4% vs. 3.9%). DMSI total scores were more highly correlated with a clinician-rated measure of manic symptoms than with measures of depression and anxiety. More patients with bipolar depression met the mixed features specifier than patients with MDD. Amongst patients with MDD, those with mixed features more frequently had a family history of bipolar disorder, were more frequently diagnosed with anxiety disorders, attention deficit disorder, and borderline personality disorder, more frequently had attempted suicide, and were more severely depressed, anxious, and irritable.

CONCLUSION: The DMSI is a reliable and valid measure of the presence of the DSM-5 mixed features specifier in depressed patients as well as the severity of the features of the specifier.