Primary care Screening Questionnaire for Depression: Reliability and validity of a new four-item tool

Abstract

Background Unidentified depression in primary care is a public health concern, globally. There is a need for brief, valid and easily administered tools in primary care. Aims To estimate reliability and validity of the newly developed Primary care Screening Questionnaire for Depression (PSQ4D), a four-item tool, with ‘yes’ or ‘no’ options. Method PSQ4D was administered verbally (time required, <1 min) by primary care physicians to adult outpatients (n=827) in six primary care settings in Kerala, India. A psychiatrist evaluated each patient on the same day, using ICD-10 Diagnostic Criteria for Research, based on unstructured clinical interview. Results The Cronbach's alpha for internal consistency reliability was 0.80; kappa coefficient for test-retest reliability was 0.9 and that for interrater reliability was 0.72. At a score ≥2, sensitivity was 0.96, specificity was 0.87, positive predictive value was 0.74, negative predictive value was 0.98, positive likelihood ratio was 7.4 and negative likelihood ratio was 0.05. Conclusions When physician administered, PSQ4D has good reliability. At a cut-off score of ≥2, it has high sensitivity and specificity to identify depressive disorder in primary care.