Table II.

Preoperative ranked predictors of prolonged length of stay following stepwise multiple regression

Rank	Predictor variable	Regression (r2)	Pearson correlation	Odds ratio (95% CI)	p-value†
1	Day-before-surgery admission	0.160	0.400	6.4 (5.2 to 7.9)	< 0.001
2	Aged 75 yrs or older at procedure	0.199	0.264	3.2 (2.6 to 3.9)	< 0.001
3	Arthroplasty of knee joint	0.212	0.121	1.6 (1.4 to 2.0)	< 0.001
4	ASA grades 3 and 4*	0.225	0.194	3.5 (2.6 to 4.6)	< 0.001
5	Female sex	0.232	0.127	1.7 (1.4 to 2.0)	< 0.001

^*Within the PLOS cohort, the proportion of ASA grade 3 or 4 patients over 75 yrs was significantly greater compared to patients under 75 yrs; 29% (101/346) vs 18% (81/460); p < 0.001. No difference was observed in the proportion of PLOS male patients vs female patients within ASA grade 3 or 4; 23% (65/283) vs 22% (117/523); p = 0.847. Marital status, BMI and consultant were found not to be predictors of PLOS.

^†Multuple regression analysis.

ASA, American Society of Anesthesiologists; CI, confidence interval.