Twenty-five studies (total number of participants unclear) were included in the final analysis; 41 studies met review inclusion criteria, but were excluded from the meta-analyses because they did not report appropriate data.
Major depressive disorder (11 studies, 1,735 participants, median 128, range 61 to 501) data were pooled at HADS cut-off values for a positive diagnosis of ≥8, ≥9, ≥10 and ≥11; not all studies provided data for all analyses. Sensitivity and specificity varied with cut-off value. At a cut-off of ≥8 (seven studies) pooled sensitivity was 0.82 (95% CI 0.73 to 0.89) and pooled specificity was 0.74 (95% CI 0.60 to 0.84). Between-study heterogeneity was low (28%).
Any depressive disorder (16 studies, 3,244 participants, median 108, range 69 to 1,078) studies could only be pooled for the cut-off value of ≥8 (16 studies). Pooled sensitivity was 0.72 (95% CI 0.62 to 0.80) and pool specificity was 0.86 (95% CI 0.79 to 0.90). Between-study heterogeneity was high (86%).
Generalised anxiety disorder (seven studies, 2,191 participants, median 132, range 100 to 1,078) studies could only be pooled for the cut-off value ≥8 (seven studies). Pooled sensitivity was 0.78 (95% CI 0.68 to 0.85) and pooled specificity was 0.74 (95% CI 0.60 to 0.82). Between-study heterogeneity was high (92%).
The authors stated that data were insufficient to support regression analyses, but reported results for the any depressive disorder analysis; only sample size was found to significantly affect estimates of test performance.