Table 6.

Diagnostic performance of the 4DSQ and HADS depression scales with respect to detecting moderate and severe major depressive disorder (prevalence 26%)*

4DSQ depression	sensitivity	specificity	PPV	NPV
≥2	0.96	0.38	0.36	0.97
≥3	0.87	0.52	0.39	0.92
≥4	0.78	0.65	0.45	0.89
≥5	0.64	0.73	0.46	0.85
≥6	0.59	0.79	0.51	0.84
≥7	0.46	0.87	0.55	0.82
≥8	0.39	0.91	0.61	0.81
≥9	0.27	0.93	0.58	0.78
≥10	0.21	0.97	0.70	0.77
HADS depression
≥8	0.96	0.30	0.33	0.96
≥9	0.91	0.38	0.35	0.92
≥10	0.87	0.48	0.37	0.91
≥11	0.81	0.56	0.40	0.89
≥12	0.64	0.65	0.40	0.84
≥13	0.56	0.72	0.42	0.82
≥14	0.49	0.82	0.49	0.82
≥15	0.39	0.85	0.48	0.79
≥16	0.27	0.90	0.50	0.77
≥17	0.22	0.95	0.59	0.77

* For each scale three cut-off points are highlighted in bold type: the optimal cut-off point with the best balance between sensitivity and specificity, the best lower cut-off point with a sensitivity ≥0.85, and the best higher cut-off point with a specificity ≥0.85

4DSQ = Four-Dimensional Symptom Questionnaire

HADS = Hospital Anxiety and Depression Scale

PPV = positive predictive value

NPV = negative predictive value