Sensitivity and specificity of Aboriginal-developed items to supplement the adapted PHQ-9 screening measure for depression: results from the Getting it Right study

Objective: To determine the psychometric properties of an Aboriginal and Torres Strait Islander-developed depressive symptom screening scale. Design: Prospective diagnostic accuracy study. Setting: Ten primary health care services or residential alcohol and other drug rehabilitation services in Australia that predominantly serve Aboriginal and Torres Strait Islander peoples. Participants: 500 adults (18 years or older) who identified as Aboriginal and/or Torres Strait Islander and were able to communicate sufficiently to respond to questionnaire and interview questions. Recruitment occurred between 25 March 2015 and 2 November 2016. Main outcome measure: Criterion validity of seven Aboriginal and Torres Strait Islander-developed items, using the adapted Patient Health Questionnaire 9 (aPHQ-9) and depression module of the Mini International Neuropsychiatric Interview (MINI) 6.0.0 as the criterion standards. Results: The seven-item scale had good internal consistency (α = 0.83) and correlated highly with the aPHQ-9 (ρ = 0.76). All items were significantly associated with diagnosis of a current major depressive episode. Discriminant function and decision tree analysis identified three items forming a summed scale that classified 85% of participants correctly. These three items showed equivalent sensitivity and specificity to the aPHQ-9 when compared with the MINI-identified diagnosis of a current major depressive episode. Conclusion: Three items developed by and for Aboriginal and Torres Strait Islander people may provide effective, efficient and culturally appropriate screening for depression in Aboriginal and Torres Strait Islander health care contexts.