SEVERITY OF ILLNESS SCORING SYSTEMS TO ADJUST NOSOCOMIAL INFECTION-RATES - A REVIEW AND COMMENTARY

Background: Nosocomial infections (NI) are often used by hospitals for external comparisons. In the National Nosocomial Infection Surveillan ce system, NI rates from intensive care units (ICUs) are adjusted for extrinsic risk factors such as device use but would be enhanced if the y were better adjusted with a direct measurement of patients' severity of illness. Method: We performed a Medline search on the literature d uring 1991 to 1996 to identify a severity of illness scoring system (S ISS) that would be useful for further adjusting ICU NI rates. We asses sed the scoring system for objectivity, simplicity, discriminating pow er, and availability. Results: Eleven studies reported the use of SISS . Seven used scoring systems developed to predict mortality rates. Fou r correlated SISS with all sites of NI and, in general, did not meet w ith success. Six showed some predictive value between SISS and nosocom ial pneumonia. The Acute Physiology and Chronic Health Evaluation scor e (version II or III), used in five studies, was the most commonly use d SISS but performed inconsistently and may not be available in many I CUs. Conclusion: New approaches for measures of severity of illness ne ed to be developed to adjust NI rates. Until such measures are availab le, comparative NI rates will be limited in their use as definitive in dicators of quality of care.