OBJECTIVETo examine whether nosocomial infection risk increases with APACHE II score, which is an index of severity-of-illness, in intensive care unit (ICU) patients.

METHODSUsing the Japanese Nosocomial Infection Surveillance database, 8,587 patients admitted to 34 participating ICUs between July 2000 and May 2002, aged 16 years or older, who had stayed in the ICU for 2 days or longer, had not transferred to another ICU, and had not been infected within 2 days after ICU admission, were followed until ICU discharge, Day 14 after ICU admission, or the development of nosocomial infection. Adjusted odds ratios with their 95% confidence intervals for nosocomial infections were calculated using logistic regression models, which incorporated sex, age, operation, ventilator; central venous catheter, and APACHE II score (0-5, 6-10, 11-15, 16-20, 21-25, 26-30, and 31+).

RESULTSThere were 683 patients with nosocomial infections. Adjusted odds ratios for nosocomial infections gradually increased with APACHE II score. Women and elective operation showed significantly low odds ratios, while urgent operation, ventilator, and central venous catheter showed significantly high odds ratios. Age had no significant effect on the development of nosocomial infection.

CONCLUSIONSNosocomial infection risk increases with APACHE II score. APACHE II score may be a good predictor of nosocomial infections in ICU patients.