Objective: To assess the risk of nosocomial infection in transferred patients and to determine whether transfer is only a risk marker or is independently associated with nosocomial infection.
Design: Retrospective analysis.
Setting: A 400-bed general hospital in the Paris area.
Patients: All the patients hospitalized on the days of the surveys were included.
Methods: Epidemiological analysis of data collected in four annual nosocomial infection prevalence surveys conducted between 1993 and 1996.
Results: Of the 1,326 patients included in the four surveys, 70 (5.3%) had been transferred from another hospital and 199 (15.0%) from another ward of our hospital. Transferred patients more frequently had known risk factors of nosocomial infection: age >65 years (P<10(-5)), a length of hospital stay >7 days on the day of the survey (P<10(-6)), at least one invasive procedure (34.2% vs 27.2%; P<.05), a recent surgical intervention (P<.05), and an immunosuppression (P<.01). The prevalence rate of infected patients was 6.7% (95% confidence interval, 5.3-8.1). The risk of being infected on a given day was more than 4 times higher in transferred patients (P<10(-6)); however, the risk was similar between patients transferred from another hospital (20.0%) and patients transferred within the hospital (17.1%). The multivariate analysis performed by logistic regression showed that intrahospital transfer, a length of hospital stay >7 days, and having had at least one invasive procedure were independent risk factors of infection.
Conclusion: According to this study, patient transfer is both a risk marker (associated with several known risk factors) and independently associated with nosocomial infection. The origin of a transferred patient is readily known at admission. It would be useful to adopt specific measures for such patients, particularly if they have other risk factors of nosocomial infection, both to protect them and to prevent transmission of the infection to other hospitalized patients.