Methods for estimating days of hospitalization due to nosocomial infections.

While there is little agreement at the individual patient level of analysis, estimates of mean NI-attributed days of stay for the two methods were essentially the same. The lack of agreement at the individual patient level may reflect fundamental differences in the methods used to derive these estimates: incorporation of noninfected patient data versus exclusive reliance on data from infected patients; and, focus on length of stay rather than the actual care being received. The potential advantages of the AEP-based method include the following: 1) all patients with NI can be included in developing estimates; 2) estimates are based on the care provided rather than simple length of stay differences; 3) data on which to form the NI-day estimates are readily available in the medical record; 4) the AEP is a validated and commonly used utilization review instrument; 5) the AEP-based method has acceptable reliability; 6) this method is designed to provide individual and group estimates of NI-attributed days; 7) because every day of stay is reviewed, additional information is available, which results in greater precision of study of the development, diagnosis, and treatment of the NI relative to the other care that originally brought the patient into the hospital. The AEP-based method for estimating NI-days is a promising alternative to the historical cohort approach. Additional applications of this approach are encouraged to further assess its reliability,validity, and additional information yield.