Introduction: Depression is one of the most common mental disorders and a leading cause of disability worldwide. It constitutes a serious public health problem, particularly among elderly individuals. Most depressed elderly patients are treated by primary care (PC) physicians. The "Patient Health Questionnaire" (PHQ-2) is an instrument used for the detection of depression in PC settings.
Objective: Evaluate the performance of the PHQ-2 in a low-income and uneducated elderly PC population.
Methods: A non-probabilistic population sample of 142 individuals was selected from the healthcare unit's users ≧ 60 years. Criterion validity was assessed by estimating the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the PHQ-2 in comparison with the structured interview using the DSM-IV. The estimates of sensitivity and specificity were obtained from varying cut-offs of the PHQ-2 score. A Receiver Operator Characteristic (ROC) curve was constructed and the area under the curve (AUC) was calculated.
Results: The group was predominantly female (73.9%), with low education level (mean 3 years of schooling). The mean age was 72.5 years old. The prevalence of depression was 26.1%. The best values of sensitivity (0.74), specificity (0.77), PPV (0.50) e NPV (0.90) were obtained with score equal to 1. The AUC was 0.77, indicating a modest performance of the test accuracy.
Conclusion: The simplicity of the PHQ-2 is an advantage for its use in PC. The high NPV indicated that 90% of those who tested negative would not need additional tests. However, the low PPV indicated that the PHQ-2 is not sufficient to screen for depression. The application of the instrument could be the first step of the screening, that would include a second step to all those with positive tests formerly.