Table III.

The statistical properties of the optimal RUSHU cut-off values for predicting nonunion at six and 12 weeks.

Variable	Nonunion	Union	Predictive value
RUSHU cut-off at 6 weeks (n = 204)
8 points or less (n = 100)	66	34	PPV = 0.66
9 points or more (n = 104)	16	88	NPV = 0.85
	Sensitivity = 0.80	Specificity = 0.72	p < 0.001*
RUSHU cut-off at 12 weeks (n = 206)
9 points or less (n = 93)	70	23	PPV = 0.75
10 points or more (n = 113)	14	99	NPV = 0.86
	Sensitivity = 0.83	Specificity = 0.81	p < 0.001*

^*Chi-squared test; statistically significant.

NPV, negative predictive value (probability of union if RUSHU is above set threshold); PPV, positive predictive value (probability of nonunion if RUSHU is below set threshold); RUSHU, Radiographic Union Score for HUmeral Fractures.