Hospital stay length as an effect modifier of other risk factors for nosocomial infection

This paper addresses the problem of hospital stay length as a risk factor for nosocomial infection and as a modifier of the effect of other risk factors for hospital infection. Patients were selected form two cross-sectional studies done in two different seasons of 1986. Risk of infection rose fairly steadily as hospital stay lenght increased (correlation coefficient: 0,83, p<0.01). Several risk factors (operation, underlying disease, and age) were analyzed on the basis of 1) raw data and 2) data stratified by lenght of stay. The results showed that hospital stay lenght is a strong modifier of the remaining risk factors, generally reducing, their effect on the development of hospital infection as length of stay increases.Corresponding author.