Patient health questionnaire-9 versus Edinburgh postnatal depression scale in screening for major depressive episodes: a cross-sectional population-based study.

Background: Major depressive episodes (MDE) are frequent at the population level and are generally associated with severe symptoms that impair performance of activities of daily living of individuals suffering from this condition. The aim of this study was to compare the accuracy of two tests that separately showed suitable properties in screening for MDE: the Patient Health Questionnaire-9 (PHQ-9) and the Edinburgh postnatal depression scale (EPDS).

Methods: In a previous study, the sensitivity and specificity of the PHQ-9 and the EPDS in screening for MDE were compared with a structured diagnostic interview conducted by psychiatrics and psychologists using the Mini International Neuropsychiatric Interview as the gold standard. In a sample of adults living in the community in Pelotas, Brazil, the PHQ-9 and EPDS were applied at the same interview and the gold standard on a median of 17 days later. The interviews were carried out at the participant's home.

Results: 447 individuals (191 men and 256 women) were assessed. The PHQ-9 and the EPDS results were concordant in 87.5 % of the respondents, with a moderate agreement beyond what was expected by chance alone (kappa = 0.61). The areas below the ROC curves were not statistically different (82.1 % for PHQ-9 and 83.5 % for EPDS) (p = 0.291), thus indicating that the two tests had similar moderate accuracy.

Conclusions: PHQ-9 and EPDS may be applied with equal confidence in screening for MDE in the community.