Table 3

Final logistic regression model

Parameter	Comparator	All subjects (n = 1875)					Hips only (n = 918)		Knees only (n = 957)
Parameter	Comparator	Beta	SE	p	ORT	95%CI	ORT	95%CI	ORT	95%CI
Intercept		3.7325	1.5273	0.0145
Age	per yr	0.0344	0.0056	< 0.0001	1.035	1.024–1.046	1.036	1.021–1.052	1.031	1.013–1.048
Female sex	v. males	0.3489	0.1676	0.0373	1.418	1.021–1.969	1.169	0.731–1.870	1.681	1.052–2.684
Weight	per kg	−0.0304	0.00402	< 0.0001	0.970	0.962–0.978	0.972	0.961–0.983	0.965	0.954–0.976
Preoperative Hgb	per g/dl	−0.0502	0.00510	< 0.0001	0.951	0.942–0.961	0.959	0.945–0.973	0.945	0.932–0.958
Regional anesthesia	v. GA	−0.3166	0.1350	0.	0.729	0.559–0.949	0.646	0.443–0.944	0.825	0.564–1.208
Surgery time	per min	0.0166	0.0018	< 0.0001	1.017	1.013–1.020	1.020	1.014–1.025	1.014	1.009–1.020
Revision surgery	v. primary	0.1235	0.1972	0.5311	1.132	0.769–1.666	1.073	0.608–1.895	1.080	0.630–1.853

CI = confidence interval; GA = general anesthesia; ORT = odds ratio for transfusion; SE = standard error.