• Maja Hansson, Jayanti Chotai, Annika Nordstöm, and Owe Bodlund.
• Division of Psychiatry, Department of Clinical Science, Umeå University, Umeå, Sweden. maja.hansson@psychiat.umu.se
• Br J Gen Pract. 2009 Sep 1; 59 (566): e283e288e283-8.

BackgroundMore than half of patients with depression go undetected. Self-rating scales can be useful in screening for depression, and measuring severity and treatment outcome.AimThis study compares the Hospital Anxiety and Depression Scale (HADS) and the Patient Health Questionnaire (PHQ-9) with regard to their psychometric properties, and investigates their agreement at different cut-off scores.MethodSwedish primary care patients and psychiatric outpatients (n = 737) who reported symptoms of depression completed the self-rating scales. Data were collected from 2006 to 2007. Analyses with respect to internal consistency, factor analysis, and agreement (Cohen's kappa) at recommended cut-offs were performed.ResultsBoth scales had high internal consistency (alpha = 0.9) and stable factor structures. Using severity cut-offs, the PHQ-9 (> or =5) diagnosed about 30% more patients than the HADS depression subscale (HADS-D; > or =8). They recognised the same prevalence of mild and moderate depression, but differed in relation to severe depression. When comparing recommended screening cut-offs, HADS-D > or =11 (33.5% of participants) and PHQ-9 > or =10 (65.9%) agreement was low (kappa = 0.35). Using the lower recommended cut-off in the HADS-D (> or =8), agreement with PHQ-9 > or =10 was moderate (kappa = 0.52). The highest agreement (kappa = 0.56) was found comparing HADS-D > or =8 with PHQ-9 > or =12. This also equalised the prevalence of depression found by the scales.ConclusionThe HADS and PHQ-9 are both quick and reliable. The HADS has the advantage of evaluating both depression and anxiety, and the PHQ-9 of being strictly based upon the Diagnostic and Statistical Manual of Mental Disorders. The agreement between the scales at the best suitable cut-off is moderate, although the identified prevalence was similar. This indicates that the scales do not fully identify the same cases. This difference needs to be further explored.

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