Validity of the PHQ-9 and PHQ-2 to screen for depression in nationwide primary care population in Latvia

Abstract Background Depression is highly underdiagnosed in primary care settings in Latvia. Screening for depression in primary care is potentially an efficient way to find undetected case s and improve diagnostics. We aimed to validate both a nine-item and two-item Patient Health Questionnaire (PHQ-9 and PHQ-2) in the Latvian and Russian languages in primary care settings using a representative sample in Latvia. Materials and methods The study was carried out within the framework of the National Research Program BIOMEDICINE to assess the prevalence of mental disorders at 24 primary care facilities. During a 1-week period, all consecutive adult patients were invited to complete the PHQ-9 and PHQ-2. Criterion validity was assessed against the Mini International Neuropsychiatric Interview (MINI). Results There were 1467 patients who completed the PHQ-9 and the MINI. Overall, the PHQ-9 items showed good internal reliability (Cronbach’s alpha 0.81 for Latvian version and 0.79 for Russian version of the PHQ-9). A cut-off score of 8 or greater was established for the PHQ-9 (sensitivity 0.75 and 0.79, specificity 0.84 and 0.80 for Latvian and Russian languages, respectively). For the PHQ-2, a score of 2 or higher (sensitivity 0.79 and 0.79, specificity 0.65 and 0.67 for Latvian and Russian languages) detected more cases of depression than a score of 3 or higher. Conclusions We suggest GPs ask patients to respond to the first 2 questions of the PHQ-9. If their score is positive, the patients should then complete the PHQ-9