Use of hierarchical models to evaluate performance of cardiac surgery centres in the Italian CABG outcome study

Table 3 Coefficients, Standard Errors (SE), SE/Coefficient ratios estimated by the single-level and the multilevel logistic model

	Single-level logistic model			Multilevel logistic model
Patient Risk Factors	Coefficients	SE	SE/Coeff.	Coefficients	SE	SE/Coeff.
Age	-0.04	0.05	-1.25	-0.05	0.04	-0.80
Age ²	0.00	0.00	-	0.00	0.00	-
Gender (fem)	0.26	0.11	0.42	0.23	0.11	0.48
Shock	1.24	0.58	0.47	1.39	0.71	0.51
Diabetes	0.30	0.10	0.33	0.28	0.10	0.36
Dialysis	1.23	0.64	0.52	1.19	0.63	0.53
Pulmonary hypertension	0.82	0.77	0.94	0.64	0.65	1.02
Malignant ventricular arrhythmia	0.38	0.28	0.74	0.37	0.29	0.78
Chronic obstructive pulmonary disease	0.42	0.15	0.36	0.41	0.15	0.37
Serum creatinine>2 mg/dl	0.73	0.26	0.36	0.87	0.30	0.34
Extra-cardiac arteriopathy	0.54	0.13	0.24	0.64	0.15	0.23
Unstable angina	0.43	0.12	0.28	0.46	0.13	0.28
Previous CABG	1.05	0.45	0.43	1.17	0.52	0.44
Emergency	1.36	0.44	0.32	1.43	0.50	0.35
Ejection fraction (vs ≥ 50)
30–49	0.59	0.14	0.24	0.60	0.15	0.25
<30	1.15	0.46	0.40	1.27	0.54	0.43
missing	0.30	0.41	1.37	0.34	0.46	1.35

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