Three predictive scores compared in a retrospective multicenter study of nonunion tibial shaft fracture

Table 1 Example of data collection

Patient	Age at the surgery	S1DE	Sex	Type of fracture (AO/OTA)	Fracting score	NURD score	LEG-NUI score	Union	Non-union	Follow-up (months)
1	22	DX	M	4.2C	9	7	5		X	18
2	28	SN	M	4.2A	6	5	6	X		12
3	82	DX	M	4.2A	6	5	4		X	12

NURD: Nonunion Risk Determination; LEG-NUI: Leeds-Genoa Nonunion Index.

Table 2 Descriptive statistics for scores and age on outcome of nonunion and sex

	Female (n = 47)		Male (n = 83)		Total
	Nonunion (n = 7)	Union (n = 40)	Nonunion (n = 34)	Union (n = 49)
Age
Min/Max	32/84	18/86	19/82	18/87	18/87
Med (IQR)	52 (43; 55.5)	54 (42.2; 62)	45 (28.2; 57.8)	45.0 (27; 60)	46.5 (34; 60)
mean ± SD	52.1 ± 16.4	52.5 ± 17.5	44.6 ± 17.9	44.5 ± 20.0	47.4 ± 18.7
FRACTING
Min/Max	5.0/10	1.0/10.0	5.0/10.0	2.0/9.0	1.0/10.0
Med (IQR)	8.0 (6.0; 9.5)	5.0 (3.0; 7.0)	8.0 (6.0; 9.0)	4.0 (3.0; 7.0)	6.0 (4.0; 8.0)
mean ± SD	7.7 ± 2.1	5.2 ± 2.3	7.8 ± 1.8	5.1 ± 2.2	6.0 ± 2.4
NURD
Min/Max	0/7.0	0/8.0	1.0/11.0	0/8.0	0/11.0
Med (IQR)	1.0 (1.0; 3.5)	1.0 (1.0; 3.0)	4.5 (3.0; 7.0)	2.0 (1.0; 4.0)	3.0 (1.0; 4.0)
mean ± SD	2.4 ± 2.4	1.8 ± 1.8	4.9 ± 2.8	2.9 ± 2.1	3.1 ± 2.5
LEG-NUI
Min/Max	1.0/6.0	0/7.0	1.0/6.0	1.0/6.0	0/7.0
Med (IQR)	3.0 (2.0; 4.0)	2.0 (1.0; 3.0)	4.0 (3.2; 5.0)	2.0 (1.0; 3.0)	2.0 (1.0; 4.0)
mean ± SD	3.1 ± 1.7	2.1 ± 1.5	4.1 ± 4.1	2.2 ± 1.2	2.7 ± 1.6

FRACTING: FRACTure prediction healING days; NURD: Nonunion Risk Determination; LEG-NUI: Leeds-Genoa Nonunion Index.

Table 3 Patients grouped by age

Age	Nonunion (%)	Union (%)	Total (%)
18-45	21 (34)	41 (66)	62 (48)
46-60	13 (35)	24 (65)	37 (28)
> 60	7 (23)	24 (77)	31 (24)

Table 4 Nonunion risk determination confusion matrix

	Union	Nonunion	Total
Predicted union	89	37	126
Predicted nonunion	0	4	4
Total	89	41	130

Table 5 Tibia FRACTure prediction healING days confusion matrix

	Union	Nonunion	Total
Predicted union	77	15	92
Predicted nonunion	12	26	38
Total	89	41	130

Table 6 Leeds-Genoa Nonunion Index confusion matrix

	Union	Nonunion	Total
Predicted union	81	17	98
Predicted nonunion	8	24	32
Total	89	41	130

Table 7 Score evaluation performance metrics

Score	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)	F-measure (%)
FRACTING	63.41	86.52	68.42	83.70	67.00
NURD	14.63	96.63	/	70	18
LEG-NUI	58.54	91.07	75.31	83.27	58.06

FRACTING: FRACTure prediction healING days; NURD: Nonunion Risk Determination; LEG-NUI: Leeds-Genoa Nonunion Index.