Table 3.

Risk Factors associated with S. aureus infection: Multivariable Cox regression analysis results

Variable	Patients who experienced a SAI in the 365-day follow-up period (N = 1430) compared to patients who did not experience a SAI (N = 72,897)
	HR	95% CI	p-value
Age at index	1.02	1.01–1.02	p < 0.001
Female sex	0.62	0.56–0.70	p < 0.001
Index surgery type
Hip; N (%)	- Reference -
Knee; N (%)	0.84	0.73–0.98	p = 0.024
Spine; N (%)	0.97	0.86–1.10	p = 0.686
CCI (12 months baseline period)	1.13	1.11–1.15	p < 0.001
Length of index hospitalization in days	1.02	1.01–1.02	p < 0.001
Complications due to prosthetic devices/ implants/grafts during index hospitalization	1.27	1.05–1.54	p = 0.012
Recent fractures at the location of index surgery (3 months baseline period)	2.05	1.81–2.32	p < 0.001
Bacterial infections (not caused by any Staphylococci) during index hospitalization	1.38	1.16–1.64	p < 0.001
Number of outpatient prescriptions of antibiotics (12 months baseline period)	1.06	1.03–1.09	p < 0.001

HRs are based on a conducted multivariable Cox regression analysis with time to first S. aureus infection after index surgery as the dependent variable. CCI Charlson Comorbidity Index, S aureus, Staphylococcus aureus, SAI Staphylococcus aureus infection