ESTIMATION OF INCREASED HOSPITAL STAY DUE TO NOSOCOMIAL INFECTIONS INSURGICAL PATIENTS - COMPARISON OF MATCHED GROUPS

An investigation, using a prospective cohort study, was performed to e stimate the prolongation of hospital stay caused by nosocomial infecti ons in surgical patients. An evaluation of the one-to-one matching met hod, as a model for similar studies was also undertaken. Between 1992 and 1994, 225 of 1482 surgical patients (15%) developed infection. Of these, 223 evaluable patients were compared with 1256 uninfected cases , in an unmatched analysis. In a further analysis, 151 infected cases were matched one-to-one with uninfected controls, and other factors su ch as age, length of preoperative stay, presence of malignancy or diab etes and presence of foley catheters or drains, were evaluated. Patien ts with infection were hospitalized for 10.6 days longer than the matc hed controls. In the unmatched analysis, infected patients appear to r emain in hospital for a further 17 days. The difference in the prolong ation of stay between matched and unmatched groups indicates the impor tance of matching as an essential model for such studies. In cases whe re matching cannot be performed, the median can be a good alternative measure to the arithmetic mean.