Table 3

Predictive ability of combinations of significant predictors

Outcome	Characteristic (%)	Events (%)		Percentage of events	Percentage correct	Sensitivity	Specificity	PPV	NPV	NNT 50	NNT 33	NNT 25	AE 50	AE 33	AE 25
Outcome	Characteristic (%)	Yes	No	Percentage of events	Percentage correct	Sensitivity	Specificity	PPV	NPV	NNT 50	NNT 33	NNT 25	AE 50	AE 33	AE 25
‘Medical’ complications n: 327	Age ≥80 years (12.3)	118 (11.9)	872	36.1	86.5	36.09	88.67	0.12	0.97	17	25	34	59	39	30
	Walking aids (24.2)	187 (9.6)	1753	57.2	76.4	57.19	77.22	0.10	0.98	21	31	41	94	62	47
	Hypertension (52.4)	221 (5.3)	3982	67.6	49.0	67.58	48.25	0.05	0.97	38	57	76	111	74	55
	Anticoagulants (5.0)	42 (10.5)	357	12.8	92.0	12.84	95.36	0.11	0.96	19	29	38	21	14	11
	Anaemia (12.4)	94 (9.4)	904	28.7	85.8	28.75	88.25	0.09	0.97	21	32	42	47	31	24
	Psychological disorder (11.6)	78 (8.4)	851	23.9	86.3	23.85	88.94	0.08	0.96	24	36	48	39	26	20
	Pulmonary disease (7.4)	46 (7.7)	551	14.1	89.6	14.07	92.84	0.08	0.96	26	39	52	23	15	12
	≥3 predictors (14.3)	147 (12.9)	996	45.0	85.3	44.95	87.05	0.13	0.97	16	23	31	74	49	37
	≥4 predictors (4.3)	68 (19.8)	275	20.8	93.3	20.80	96.43	0.20	0.97	10	15	20	34	23	17
	≥5 predictors (0.9)	24 (32.4)	50	7.3	95.6	7.34	99.35	0.32	0.96	6	9	12	12	8	6
	≥4 MP2 (18.1)	174 (12.0)	1276	53.2	82.2	53.21	83.42	0.12	0.98	17	25	33	87	58	44
	≥5 MP2 (12.8)	139 (13.6)	886	42.5	86.6	42.51	88.48	0.14	0.97	15	22	29	70	46	35
	≥2 MPEH (19.1)	182 (11.9)	1348	55.7	81.4	55.66	82.50	0.12	0.98	17	25	34	91	61	46
	≥3 MPEH2 (5.6)	83 (18.5)	366	55.7	92.4	25.38	95.14	0.18	0.97	11	16	22	42	28	21
‘Severe medical’ complications n:213	Age ≥80 years (12.3)	70 (7.0)	928	36.8	87.1	36.84	88.32	0.07	0.98	29	43	57	35	23	18
	Walking aids (24.2)	108 (5.5)	1861	56.8	76.1	56.84	76.57	0.05	0.99	36	55	73	54	36	27
	Anticoagulants (4.9)	27 (6.7)	378	14.2	93.3	14.21	95.24	0.07	0.98	30	45	60	14	9	7
	Psychological disorder (11.6)	48 (5.1)	895	25.3	87.2	25.26	88.73	0.05	0.98	39	59	79	24	16	12
	Pulmonary disease (7.5)	31 (5.11)	577	16.3	90.9	16.32	92.73	0.05	0.98	39	59	78	16	10	8
	≥2 predictors (14.9)	92 (7.6)	1122	48.4	85.0	48.42	85.87	0.08	0.99	26	40	53	46	31	23
	≥3 predictors (3.1)	31 (12.4)	218	16.3	95.4	16.32	97.26	0.12	0.98	16	24	32	16	10	8
	≥4 predictors (0.3)	6 (23.1)	20	3.2	97.5	3.16	99.75	0.23	0.98	9	13	17	3	2	2
	≥3 MP (14.3)	83 (7.3)	1060	43.7	85.5	44.62	86.47	0.07	0.99	28	41	55	42	28	21
	≥4 MP2 (18.1)	98 (7.0)	1352	51.6	82.1	52.69	82.74	0.07	0.99	30	44	59	49	33	25
	≥2 MPEH (19.1)	103 (6.7)	1427	54.2	81.2	55.38	81.79	0.07	0.99	30	45	59	52	34	26

Number of included patients is 8021 for ‘medical’ complications and 8132 for ‘severe medical’ complications due to 8.1% and 6.9% with missing data on relevant predictors.
AE 25, avoided events in the cohort with 25% event reduction; AE 30, avoided events in the cohort with 30% event reduction; AE 50, avoided events in the cohort with 50% event reduction; MP2, ‘medical’ predictors with two points if OR ≥1.9; MPEH, medical predictors excluding hypertension; MPEH2, ‘medical’ predictors excluding hypertension and two points if OR ≥1.9; NNT 25, number needed to treat if there is a 25% event reduction; NNT 30, number needed to treat if there is a 30% event reduction; NNT 50, number needed to treat if there is a 50% event reduction; NPN, negative predictive value; PPV, positive predictive value.