Table 4.

Results of the multilevel logistic regression models.

Variable	Empty model OR (95% CI)	Multivariate model OR (95% CI)	P value
ASA score (1, 2 vs. 3, 4)		1.40 (1.11–1.78)	0.005
Duration of follow-up (≤ 36 vs. > 36 days)		0.01 (0.01–0.03)	< 0.0001
MOR (95% CI)	2.50 (1.99–3.20)	2.94 (2.33–3.84)

OR, odds ratio; CI, confidence interval; MOR, median odds ratio.