Validation of screening tools for depression and anxiety disorders in a primary care population with high HIV prevalence in Zimbabwe.

BACKGROUND: In low income countries in Sub-Saharan Africa there are few validated tools to screen for common disabling mental disorders such as depression and general anxiety disorder (GAD). OBJECTIVES: We validated three screening tools: the Shona Symptom Questionnaire for common mental disorders (SSQ-14), the Patient Health Questionnaire for depression (PHQ-9), and the Generalized Anxiety Disorder questionnaire (GAD-7). The study participants were attendees at a primary health care clinic in Harare, Zimbabwe. METHODS: Consecutive adults aged 18 and above attending the clinic were enrolled over a two-week period in September 2013. Trained research assistants administered the screening tools to eligible participants after obtaining written consent. Participants were then interviewed by one of four psychiatrists using the Structured Clinical Interview of the DSM-IV (SCID). Performance characteristics were calculated for each tool, against the SCID as the gold standard. RESULTS: A total of 264 participants were enrolled, of whom 52 (20%) met the SCID criteria for depression alone, 97 (37%) for mixed depression and anxiety and 9 (3%) for anxiety alone. Of the 237 where HIV status was known, 165 (70%) were HIV positive. With the optimal cutoff of ≥9, the sensitivity and specificity for the SSQ-14 against a diagnosis of either depression and/or general anxiety were 84% (95%CI:78-89%) and 73% (95%CI:63-81%) respectively. Internal reliability was high (Cronbach α=0.74). The optimal cutoff for PHQ-9 was ≥11, which provided a sensitivity of 85% (95%CI:78-90%) and specificity of 69% (95%CI:59-77%) against a SCID diagnosis of depression (Cronbach α=0.86). The GAD-7 (optimal cutoff ≥10) had sensitivity and specificity of 89% (95%CI:81-94%) and 73% (95%CI:65-80%) respectively against a SCID diagnosis of GAD (Cronbach α=0.87). CONCLUSION: Screening tools for depression and GAD had good performance characteristics in a primary health care population in Zimbabwe with a high prevalence of HIV. These can be used for research and also in clinical care to screen patients who may benefit from treatment.