Validity of the Patient Health Questionnaire-9 (PHQ-9) for depression screening in adult primary care users in Bucaramanga, Colombia

The patient health questionnaire-9 (PHQ-9) is one of the most widely used self-report instruments in primary care. There is no criterion validity of the PHQ-9 in Colombia. The objective was to validate the PHQ-9 as a screening tool in primary care. A cross-sectional, scale criterion validity study was performed using as reference criterion the mini neuropsychiatric interview (MINI) in male and female adult users of primary care centres. We calculated the internal consistency and convergent and criterion validity of the PHQ-9 by analysing the receiver operating characteristics (ROC) and the area under the curve (AUC). We analysed 243 participants; 184 (75.7%) were female. The average age was 34.05 (median of 31 and SD = 12.47). Cronbach's α was 0.80 and McDonald's ω was 0.81. Spearman's Rho was 0.64 for HADS-D (P <0.010) and 0.70 for PHQ-2 (P <0.010). The AUC was 0.92 (95% CI 0.880-0.963). The optimal cut-off point of PHQ-9 was ≥7: sensitivity of 90.38 (95% CI: 81.41-99.36); specificity of 81.68 (95% CI: 75.93-87.42); PPV 57.32 (95% CI: 46.00-68.63); NPV 96.89 (95% CI: 93.90-99.88); Youden index 0.72 (95% CI: 0.62-0.82); LR+ 4.93 (95% CI: 3.61-6.74); LR- 0.12 (95% CI: 0.005-0.270). In sum, the Colombian version of PHQ-9 is a valid and reliable instrument for depression screening in primary care in Bucaramanga, with a cut-off point ≥7.