Table 4.

Performance of the basic instrument

Development cohort (n = 4280)
Score cutoff (greater than or equal to)	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)	No. of patients with score less than cutoff
0	100	0	63	—	0
1	99	5	65	79	107
2	97	11	65	70	243
3	92	24	68	64	581
4	84	41	71	60	1072
5	76	53	74	56	1477
6	63	69	78	52	2091
7	54	75	79	48	2435
8	38	86	83	45	3024
9	31	90	84	43	3288
10	18	95	86	40	3724
11	16	96	87	40	3793
12	13	97	88	39	3891
13	9	98	87	38	3996
14	2	99	84	37	4212
15	1	99	80	37	4240
Validation cohort (n = 2844)
Score cutoff (greater than or equal to)	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)	No. of patients with score less than cutoff
0	100	0	64	—	0
1	99	3	64	72	47
2	98	9	66	72	127
3	93	22	68	65	349
4	86	44	73	64	713
5	78	55	75	58	970
6	63	71	79	52	1399
7	55	76	80	49	1600
8	40	87	85	45	1976
9	32	91	86	43	2165
10	18	96	89	40	2483
11	16	96	89	39	2515
12	13	98	92	39	2584
13	10	99	93	38	2656
14	3	100	93	37	2783
15	2	100	92	36	2807

Abbreviations: NPV, negative predictive value; PPV, positive predictive value.