Usefulness of severity indices in intensive care medicine as a predictor of nosocomial infection risk.

To evaluate the relationship between severity and nosocomial infection in critical patients, we have conducted a prospective study at the Intensive Care Unit of the University of Granada Hospital (Spain). Patients' severity was evaluated by APACHE II and TISS. We found a positive association with nosocomial infection risk for an APACHE II score greater than 12 points (RR = 2.45) and for first-day TISS greater than 20 points (RR = 2.51). With a multivariate analysis we did not find an association between APACHE II and nosocomial infection risk, but each TISS point suggests an infection risk increment of 6%. We concluded TISS may be considered a good infection risk predictor. TISS could also be taken into account when nosocomial infection rates from several ICUs are compared.