Table II.

Covariate balance across comparison groups before and after propensity score weighting.

	Before propensity score weighting			After propensity score weighting
Variable	NPWT group (n = 266)	Standard wound dressing group(n = 1,056)	SMD	NPWT group (n = 266)	Standard wound dressing group (n = 1,056, weighted as 318)	SMD
Gustilo grade, %
II	27.4	59.5	-0.72	27.4	27.5	-0.0002
IIIA	37.2	33.1	0.09	37.2	37.2	0
IIIB	35.3	7.5	0.58	35.3	35.3	0.0002
Mechanism of injury, %
High energy	97.7	90.7	0.47	97.7	97.7	0.0008
Fracture location, %
Tibia	63.9	50.5	0.28	63.9	63.9	0.0001
Contamination, %
Mild	46.6	74.3	-0.56	46.6	46.6	-0.0001
Moderate	38.4	20.9	0.36	38.4	38.4	0
Severe	15	4.7	0.29	15	15	0.0002
Irrigation solution, %
Saline	51.1	53.7	-0.05	51.1	51.1	0.0001
Skin loss	49.6	17.5	0.64	49.6	49.6	0.0002
Muscle loss	39.9	13.6	0.54	39.9	39.8	0.0002
Propensity score, probability	0.35	0.16	0.83	0.35	0.35	-0.0005

NPWT, negative pressure wound therapy; SMD, standardized mean difference.