TABLE II.

Association of General Anesthesia with Operating Room Times and Length of Stay in Patients Who Had Undergone Hip Arthroplasty

			Bivariate Linear Regression		Propensity-Adjusted Multivariate Linear Regression§
	General Anesthesia*	Spinal Anesthesia*	Beta†	P Value‡	Beta†#	P Value‡
Preoperative room time (min)	46 ± 57	49 ± 76	−2 (−5 to +1)	0.131	−2 (−5 to +1)	0.100
Operative time (min)	99 ± 40	87 ± 38	+12 (+11 to +13)	<0.001	+12 (+11 to +13)	<0.001
Postoperative room time (min)	16 ± 14	12 ± 9	+5 (4 to +6)	<0.001	+5 (+4 to +6)	<0.001
Postoperative length of stay (d)	3.1 ± 2.3	3.1 ± 3.2	0.0 (−0.1 to +0.1)	0.099	0.0 (−0.1 to +0.1)	0.264

^*The values are given as the mean and the standard deviation.

^†The values are given as the mean with the 95% CI in parentheses.

^‡Significant values were set at p < 0.05.

^§Each line represents a separate multivariate analysis for each variable to give an adjusted beta coefficient and p value by controlling for patient characteristics and propensity score.

^#Unstandardized beta coefficient represents unit change in the outcome variable if the predictor variable is positive. For example, a significant coefficient of +12 for operative time means that, on average, general anesthesia is associated with an increase in operative time of twelve minutes.