Risk assessment for surgical-site infections in orthopedic patients

OBJECTIVE: To assess the relative importance of risk factors for surgical-s ite infections (SSIs) in orthopedic patients and thereby determine which ri sk factors to monitor in the national surveillance of SSI in The Netherland s. DESIGN: Reanalysis of data on SSI and associated risk factors from two surv eillance projects on nosocomial infections, carried out in 1992 and 1993 in The Netherlands: Project Surveillance Nosocomial Infections in the region of Utrecht (PSZU) and the first Project Surveillance Surgical Wound Infecti ons (SWIFT-1). Odds ratios (ORs) were calculated for age, gender, preoperat ive stay, and the number of operations. In addition, in PSZU, other nosocom ial infections, and, in SWIFT-1, prophylactic antibiotics, acute surgery, a nd wound contamination were studied. PARTICIPANTS: The study was confined to hospitalized orthopedic patients (P SZU, 4,872; SWIFT-1, 6,437). RESULTS: In PSZU, the following ORs were significant in a multivariate mode l: age 0-44 years, 1.0; 45-64 years, 1.6; 65-74 years, 4.7; and 75-99 years , 6.0. For a preoperative stay over 4 days, the OR was 3.3 (95% confidence interval [CI95], 2.5-4.0), and for multiple surgery, 2.5 (CI95, 1.9-3.0). F or females, the OR was 0.8 (not significant). The same model applied to SWI FT-1 gave similar ORs. Adjustment for additional nosocomial infections (PSZ U) decreased the ORs for ages over 65 years remarkably. The OR for addition al nosocomial infections in patients under 65 years of age was 15.6 (CI95, 4.3-57.4). Adjustment for prophylactic antibiotics, acute surgery, and woun d-contamination class (SWIFT-1) did not influence the ORs of the original m odel, but showed that wound-contamination class was an important risk facto r. CONCLUSIONS: Age, additional nosocomial infections, wound-contamination cla ss, preoperative stay, and the number of operations were identified as impo rtant risk factors for SSI in Dutch orthopedic patients (Infect Control Hos p Epidemiol 1999;20:402-407).