Table 2.

Multiple-regression analysis of risk factors (n = 9,987) for LOS > 2 days and attributed risk-score points

Variable	OR (95%CI)	p-value	points
Weekday of surgery
Monday	1 (ref.)	–
Tuesday	1.0 (0.9–1.2)	1.0
Wednesday	0.9 (0.7–1.0)	0.08
Thursday	0.9 (0.8–1.1)	0.4
Friday	1.5 (1.2–2.0)	< 0.01
Saturday	2.9 (0.3–30.5)	0.4
Sunday	1.4 (0.2–13.6)	0.8
Age group
< 50	1.3 (0.9–1.8)	0.08
50–60	1.2 (0.9–1.4)	0.1
61–65	1.0 (0.8–1.3)	0.9
66–70	1 (ref.)	–
71–75	1.2 (1.0–1.4)	0.1
76–80	1.4 (1.2–1.7)	< 0.01	1
81–85	2.0 (1.6–2.5)	< 0.01	2
> 85	3.4 (2.5–4.6)	< 0.01	3
BMI
< 18.5	1.6 (1.0–2.6)	0.07	0
18.5–24.9	1 (ref.)	–
25–29.9	1.0 (0.8–1.1)	0.7	0
30–34.9	1.0 (0.9–1.2)	1.0	0
35–39.9	1.2 (0.9–1.5)	0.2	0
> 39.9	1.3 (0.9–1.8)	0.1
Female sex	1.3 (1.2–1.5)	< 0.01	1
Walking aid	1.9 (1.7–2.3)	< 0.01	2
Living alone	1.6 (1.4–1.8)	< 0.01	1
Smoking	1.1 (0.9–1.3)	0.5	0
Alcohol > 24 g/day	0.8 (0.6–1.0)	0.06	0
Total knee arthroplasty	1.9 (1.7–2.1)	< 0.01	1
Psychiatric disease	1.6 (1.4–1.9)	< 0.01	1
Cardiac disease	1.2 (1.0–1.4)	0.04	1
Pulmonary disease	1.3 (1.1–1.6)	< 0.01	1
Hypertension	1.0 (0.9–1.1)	0.8	0
Diabetes mellitus
Non-insulin dependent	1.3 (1.1–1.6)	0.02	1
Insulin dependent	2.0 (1.4–2.9)	< 0.01	2
Anticoagulants	1.2 (1.0–1.5)	0.09	0
Preoperative anemia a	1.5 (1.3–1.7)	< 0.01	1

OR: odds ratio. CI: confidence interval.

^a Hemoglobin < 13 g/dL.