Table 2

Variables that predict increased LOS in hospital after primary unilateral total knee replacement, based on univariate and multivariate analysis

Variable		OR (95% CI)	p Value	aOR (95% CI)	p Value
Patient demographics
Age (years)	<60	REF		REF
	60–64	0.95 (0.66 to 1.37)	0.78	1.08 (0.73 to 1.59)	0.71
	65–69	1.37 (0.98 to 1.92)	0.07	1.42 (0.98 to 2.06)	0.06
	>70	2.04 (1.51 to 2.75)	<0.001	1.94 (1.38 to 2.73)	<0.001
Race	Malay	0.66 (0.42 to 1.03)	0.07	0.53 (0.31 to 0.92)	0.02
	Indian	1.24 (0.82 to 1.87)	0.32	1.34 (0.85 to 2.11)	0.21
	Others	1.82 (1.09 to 3.04)	0.02	1.49 (0.83 to 2.68)	0.19
	Chinese	REF		REF
Body mass index	<25	REF		REF
	25–29.9	0.90 (0.71 to 1.15)	0.41	1.02 (0.78 to 1.32)	0.91
	30–34.9	0.76 (0.56 to 1.03)	0.07	0.92 (0.65 to 1.28)	0.61
	≥35	1.18 (0.78 to 1.78)	0.43	1.56 (0.96 to 2.53)	0.07
Gender	Male	REF		REF
Gender	Female	1.15 (0.90 to 1.47)	0.25	1.20 (0.89 to 1.63)	0.23
Details of operation
Type of anaesthesia	GA	REF		REF
Type of anaesthesia	RA	0.76 (0.62 to 0.94)	0.01	0.75 (0.59 to 0.95)	0.02
Duration of operation (minutes)	≤100	REF		REF
Duration of operation (minutes)	>100	1.41 (1.09 to 1.84)	0.01	1.37 (1.03 to 1.84)	0.03
Perioperative blood transfusion (units)	None	REF		REF
	1	4.10 (2.61 to 6.45)	<0.001	2.12 (1.24 to 3.60)	0.006
	≥2	13.01 (6.46 to 26.17)	<0.001	6.71 (3.14 to 14.33)	<0.001
Repeat operation within Hhospital stay		25.48 (3.06 to 212.14)	0.003	15.22 (1.38 to 167.59)	0.03
Day of week of operation	Monday	2.20 (1.54 to 3.13)	<0.001	2.38 (1.62 to 3.49)	<0.001
	Tuesday	2.10 (1.51 to 2.93)	<0.001	2.42 (1.68 to 3.49)	<0.001
	Wednesday	1.93 (1.35 to 2.76)	<0.001	2.21 (1.50 to 3.24)	<0.001
	Thursday	REF		REF
	Friday	2.14 (1.50 to 3.06)	<0.001	1.99 (1.35 to 2.94)	0.001
	Saturday	1.38 (0.79 to 2.41)	0.25	1.46 (0.80 to 2.67)	0.22
Patient comorbidities
Anaemia	None	REF		REF
	Mild	1.97 (1.53 to 2.53)	<0.001	1.71 (1.29 to 2.27)	<0.001
	Moderate/severe	3.22 (2.29 to 4.53)	<0.001	2.29 (1.54 to 3.39)	<0.001
DM on insulin		1.55 (0.77 to 3.12)	0.22	1.20 (0.53 to 2.76)	0.66
Creatinine >2 mg/dL		4.26 (1.68 to 10.78)	0.002	2.35 (0.78 to 7.11)	0.13
Previous CVA		3.33 (1.84 to 6.01)	<0.001	2.89 (1.50 to 5.55)	0.001
IHD		1.92 (1.30 to 2.83)	0.001	1.50 (0.95 to 2.36)	0.08
CCF		2.11 (0.79 to 5.66)	0.14	1.19 (0.38 to 3.75)	0.77
Smoking		0.98 (0.69 to 1.39)	0.90	1.15 (0.76 to 1.75)	0.50
ASA-PS score	1	REF		REF
	2	1.19 (0.77 to 1.83)	0.44	0.96 (0.61 to 1.52)	0.86
	3	2.88 (1.68 to 4.92)	<0.001	1.40 (0.77 to 2.56)	0.27

aOR, adjusted OR; ASA-PS, American Society of Anesthesiologist Physical Status; CCF, congestive cardiac failure; CVA, cerebrovascular accidents; DM, diabetes mellitus; GA, general anaesthesia; IHD, ischaemic heart disease; LOS, length of stay; RA, regional anaesthesia; REF, reference.