Table 4.

Outcome measures for the most important groups and weighted average AUC for each malleolar AO type, group, and subgroup combined

	Cases	Sensitivity	Specificity
AO type	n = 409	(%)	(%)	Youden’s J	AUC (95% CI)
44A
Base	32	73	81	0.54	0.81 (0.72–0.88)
1	22	88	75	0.63	0.87 (0.77–0.94)
1.1	6	75	93	0.68	0.87 (0.70–0.98)
1.2	7	80	83	0.63	0.79 (0.54–0.94)
1.3	9	75	88	0.63	0.84 (0.70–0.95)
2	7	100	74	0.74	0.91 (0.83–0.97)
2.1	5	100	74	0.74	0.89 (0.80–0.97)
3	2	100	86	0.86	0.90 (0.83–0.96)
44B
Base	137	89	88	0.77	0.93 (0.90–0.95)
1	67	90	88	0.77	0.93 (0.88–0.96)
1.1	39	87	84	0.71	0.89 (0.85–0.93)
1.2	26	92	85	0.77	0.90 (0.81–0.96)
2	38	82	84	0.65	0.87 (0.80–0.92)
2.1	20	100	72	0.72	0.87 (0.83–0.92)
2.2	16	88	74	0.62	0.82 (0.68–0.91)
2.3	2	100	98	0.98	0.99 (0.97–1.00)
3	32	78	90	0.68	0.90 (0.85–0.94)
3.1	12	83	75	0.58	0.79 (0.63–0.90)
3.2	13	92	82	0.74	0.91 (0.84–0.96)
3.3	6	100	91	0.91	0.96 (0.93–0.98)
44C
Base	47	74	90	0.65	0.86 (0.79–0.92)
1	24	75	79	0.54	0.83 (0.72–0.91)
1.1	17	76	85	0.61	0.86 (0.74–0.94)
1.2	5	80	92	0.72	0.89 (0.77–0.97)
1.3	2	100	88	0.88	0.92 (0.86–0.97)
2	18	100	72	0.72	0.91 (0.86–0.95)
2.1	6	83	93	0.76	0.91 (0.79–0.98)
2.2	3	100	88	0.88	0.96 (0.88–1.00)
2.3	9	100	77	0.77	0.88 (0.84–0.92)
3	5	100	88	0.88	0.95 (0.90–0.98)
Malleolar	216	86	90	0.76	0.92 (0.89–0.95)
Weighted mean AUC
A					0.84
B					0.90
C					0.87
Malleolar					0.90

Criterion based on Youden’s Index (Youden 1950, Aoki et al. 1997, Shapiro 1999, Greiner et al. 2000) defined as

$$YI\left(c\right)=ma{x}_c\left(Se\left(c\right)+Sp\left(c\right)–1\right).$$

This is identical (from an optimization point of view) to the method that maximizes the sum of sensitivity and specificity (Albert 1987, Zweig and Campbell 1993) and to the criterion that maximizes concordance, which is a monotone function of the AUC.