Validation of the WHO-5 as a first-step screening instrument for depression in adults with diabetes: Results from Diabetes MILES - Australia.

Aims: Screening for depression is recommended internationally. The World Health Organization's 5-item Well-being Index (WHO-5) is used clinically to screen for depression but its empirical suitability for this purpose is not well documented. We investigated the psychometric properties of the WHO-5 and its suitability for identifying likely depression in Australian adults with diabetes.
Methods: The Diabetes MILES - Australia study dataset provided a sample of N=3249 who completed the WHO-5 (positively-worded 5-item measure of emotional well-being) and the PHQ-9 (9-item measure of depressive symptoms). Analyses were conducted for the full sample, and separately by diabetes type and treatment (type 1, non-insulin-treated type 2, and insulin-treated type 2 diabetes). Construct (convergent and factorial) validity and reliability of the WHO-5 were examined. ROC analyses were used to examine the sensitivity and specificity of the WHO-5 as a depression screening instrument, comparing two commonly used WHO-5 cut-off values (≤7 and <13) with the PHQ-9.
Results: For the whole sample, the WHO-5 demonstrated satisfactory internal consistency reliability (α=0.90) and convergent validity with the PHQ-9 (r=-0.73, p<0.001). Confirmatory factor analysis partially supported factorial validity: Χ ² (5)=834.94, p<0.001; RMSEA=0.23, 90% CI 0.21-0.24; CFI=0.98, TLI=0.96; factor loadings=0.78-0.92. The AUC was 0.87 (95% CI: 0.86-0.89, p<0.001). The sensitivity/specificity of the WHO-5 for detecting likely depression was 0.44/0.96 for the ≤7 cut-off, and 0.79/0.79 for the <13 cut-off, with similar findings by diabetes type and treatment.
Conclusions: These findings support use of a WHO-5 cut-point of <13 to identify likely depression in Australian adults with diabetes, regardless of type/treatment.
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