Association between the introduction of a national targeted intervention program and the incidence of surgical site infections in Swiss acute care hospitals

Table 3 Additional patient-based model with odds ratios adjusted (aORs) for additional covariables of age, sex, ASA score, contamination class, elective and T score (fixed effects), and body mass index (BMI)

	aOR	95% CI	P value
Postintervention (ref = preintervention)	0.70	0.56 to 0.88	0.003
Age (per year increase)	1.00	0.99 to 1.01	0.78
Sex = female, (ref = male)	0.95	0.76 to 1.19	0.65
ASA score 3–5 (ref = ASA 1 and 2)	2.10	1.56 to 2.82	< 0.001
Wound contamination class II (clean-contaminated) Ref = class 1 (clean)	4.14	1.36 to 12.57	0.01
Wound contamination class III (contaminated) Ref = class 1 (clean)	3.76	1.32 to 10.75	0.01
Elective surgery (Ref = emergency surgery)	0.67	0.52 to 0.86	0.002
Exceeding T score = yes^a (Ref = no)	1.20	0.94 to 1.53	0.136
BMI per kg/m2 increase	1.03	1.01 to 1.05	0.003

^aT-score: number (%) of procedures where the duration exceeded the 75th percentile of the operation duration

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