[Psychometric characteristics of the Patient Health Questionnaire (PHQ-9)]

Abstract

Background: Simple and brief questionnaires with adequate psychometric properties are useful for the early detection of depressive disorders.

Aim: To analyze the psychometric behavior of the Patient Health Questionnaire (PHQ-9) in Chile.

Material and methods: Data were collected from 1,738 adult patients, consulting in primary health care centers. The values obtained in the PHQ-9 were compared with those of the Composite International Diagnostic Interview (CIDI).

Results: The mean score of PHQ-9 was 4.85 ± 5.57. Internal consistency indices were high. McDonald's ω coefficient of was 0.90 and Cronbach alpha 0.89. A confirmatory factor analysis showed a good fit of the one-dimensional model. Using a cutoff score of seven determined with the receiver operating characteristic (ROC) curve, the sensitivity and specificity of the instrument were 0.8 and 0.7, when compared with CIDI diagnoses.

Conclusions: PHQ-9 is a useful instrument for the screening of depressive disorders in primary health care centers in Chile.