Table 2.

Results of multivariable models of risk factors for methicillin-resistant Staphylococcus aureus carriage on admission

Risk factor	Stepwise model			Best BMA model			BMA model				Simple model
	OR	95% CI	P	OR	95% CI	P	Posterior Probability	OR	95% CI	P	OR	95% CI	P
Female sex							2.3	1.0	0.9-1.1	.894
Age (per 1-year increment)	1.02	1.00-1.03	.009				44.8	1.01	0.99-1.03	.421	1.02	1.00-1.03	.009
Diabetes							7.8	1.0	0.8-1.4	.796
Chronic skin disease	3.0	1.5-5.8	.002				49.3	1.7	0.5-5.3	.369	2.9	1.5-5.6	.002
Hospitalisation (<1 year)	2.2	1.5-3.3	<.001	2.3	1.5-3.4	<.001	100	2.2	1.5-3.4	<.001	2.2	1.5-3.3	<.001
Nursing home resident	3.4	1.6–6.8	.001	4.2	2.1-8.3	<.001	82.4	3.1	0.9-10.3	.070	3.4	1.7-6.9	.001
Skin wound/sore	2.7	1.7-4.4	<.001	3.0	1.8-4.8	<.001	100	2.9	1.7-4.7	<.001	2.8	1.7-4.6	<.001
Antibiotics (<6 months)							2.6	1.0	0.9-1.2	.890
Urinary catheter	4.5	2.0-10.3	.018	4.3	1.9-9.6	<.001	72.4	2.9	0.7-12.8	.152
Tracheostomy							3.1	1.1	0.6-2.0	.867
C-statistics for validation dataset
Cross-validation, mean (SD)a	0.643 (0.029)			0.663 (0.028)				0.653 (0.031)			0.687 (0.030)
Athens	0.598			0.610				0.606			0.640
Barcelona	0.762			0.797				0.798			0.797
Cremona	0.585			0.641				0.601			0.670
Paris	0.585			0.579				0.627			0.686

Note. The Stepwise model used stepwise backward elimination; the Best BMA model was the model with the highest posterior probability with the Bayesian model averaging approach; the BMA model included all covariates with a posterior probability of greater than zero using Bayesian model averaging; the Simple model included variables selected at least half the time in both Stepwise and BMA models on repeated random sub-samples of 50% of the cohort. CI, confidence interval; OR, odds ratio; SD, standard deviation.

^aCross-validation by repeated random sub-sampling of 50% of the full cohort data for derivation and validation datasets.