Validation of screening instruments for common mental disorders and suicide risk in south African primary care settings.

INTRODUCTION: In South Africa, there is limited mental health infrastructure and resources. Valid screening tools are needed to facilitate identification and linkage to care. We evaluated the performance of Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7), Primary Care Post Traumatic Stress Disorder Screen for DSM-5 (PC-PTSD-5), and the Columbia Suicide Severity Rating Scale (C-SSRS) among adults in South Africa against a diagnostic gold standard.

METHODS: Adults present at healthcare facilities were screened with the PHQ-9, GAD-7, PC-PTSD-5, and the C-SSRS. Nurses used a structured diagnostic interview to identify depression, anxiety, panic disorder, PTSD and elevated suicide risk. We assessed the internal consistency, criterion validity, and the sensitivity and specificity of these tools.

RESULTS: Of the 1885 participants, the prevalence of common mental disorders and suicide risk was 24.4 % and 14.9 %, respectively. The PHQ-9, GAD-7, and PC-PTSD-5 showed good internal consistency (0.80-0.89). All screeners demonstrated good criterion validity. For depression, a cut-off of ≥5 on the PHQ-9 yielded sensitivity of 84.24 %, while ≥10 yielded sensitivity of 48.77 %. For anxiety, the GAD-7 performed similarly. A cut-off of ≥4 on the PC-PTSD yielded sensitivity of 61.96 %. The C-SSRS yielded lower sensitivity than expected.

LIMITATIONS: The prevalence data is not generalizable to the larger South African adult population given the use of a targeted, healthcare facility-based sampling and recruitment strategy.

CONCLUSIONS: The performance of the PHQ-9, GAD-7, and PC-PTSD-5 demonstrated good internal consistency and criterion validity, though sensitivity and specificity trade-offs were enhanced with lower cut-offs. Further research into suicide risk screening is warranted.