Table 5.

Diagnostic performance of the 4DSQ and HADS depression scales with respect to detecting any major depressive disorder (prevalence 49%)*

4DSQ depression	sensitivity	specificity	PPV	NPV
≥1	0.96	0.34	0.59	0.89
≥2	0.88	0.46	0.62	0.80
≥3	0.78	0.60	0.66	0.74
≥4	0.65	0.72	0.69	0.68
≥5	0.53	0.79	0.71	0.63
≥6	0.45	0.83	0.71	0.60
≥7	0.32	0.87	0.71	0.57
≥8	0.25	0.92	0.75	0.56
≥9	0.18	0.93	0.72	0.54
≥10	0.12	0.97	0.78	0.53
HADS depression
≥7	0.97	0.30	0.57	0.92
≥8	0.93	0.39	0.60	0.84
≥9	0.88	0.49	0.63	0.81
≥10	0.84	0.60	0.68	0.80
≥11	0.75	0.67	0.69	0.73
≥12	0.60	0.75	0.70	0.65
≥13	0.49	0.78	0.69	0.61
≥14	0.40	0.88	0.77	0.60
≥15	0.32	0.89	0.73	0.57
≥16	0.21	0.93	0.74	0.55
≥17	0.16	0.96	0.79	0.54

* 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