PHQ-8 Days: a measurement option for DSM-5 Major Depressive Disorder (MDD) severity

This report is based on data from the Behavioral Risk Factor Surveillance System 2006 from 198,678 survey participants who responded to all eight Patient Health Questionnaire (PHQ-8) items. We evaluated use of the days version of the PHQ-8 to determine an optimal cut-point for identifying respondents with depression and to evaluate the performance characteristics of the PHQ-8 at this cut-point.A PHQ-8 score of 55 or more days was determined to be the optimal cut-point when compared to the DSM-derived PHQ-8 algorithm for a major depressive episode (five or more symptoms present "more than half the days," at least one of which must be anhedonia or depression). In the full sample, the sensitivity and the specificity of this cut-point were 0.91 (0.90-0.93) and 0.99 (0.99-0.99), respectively.The days version of the PHQ-8 may be a valuable dimensional alternative to the traditional PHQ-8 by offering finer granularity of dimensionality (a score of 0 to 112).Diagnostic and Statistical Manual of Mental Disorders (DSM) criteria are presently designed to establish categorical diagnoses, distinguishing those with a particular mental disorder from those without such a disorder [1]. DSM criteria are currently less useful for measuring psychiatric symptoms and disorders on a continuum. Major depressive disorder is classified as a mood disorder, with diagnosis hinging on the presence of a single episode or of recurrent major depressive episodes (MDE) [1]. The gold standard for a diagnosis of depression is the Structural Clinical Interview (SCID), a diagnostic interview based on DSM criteria that requires clinical expertise to administer. It yields a dichotomous outcome, the presence or absence of MDE, for the past month (current), past year, or over a lifetime, based on the presence of five or more of the nine DSM criteria, provided that anhedonia or depression was present [1,2].The proposed draft diagnostic criteria for the fifth edition of the DSM (DSM-5; http://www.dsm5.org webc