Multivariate analysis of determinants of postoperative wound infection: a possible basis for intervention.

Multivariate analysis of variables hypothetically associated with the development of postoperative wound infection was attempted with use of large groups of patients undergoing certain surgical procedures over periods of 12-36 months. The data were obtained through prospective surveillance by specially trained nurse-epidemiologists. For patients who had colon surgery (n=261), the multivariate analysis showed that only four variables were independently associated with postoperative wound infection: more than one operation during a single episode of hospitalization (adjusted odds ratio, 7.3); Arab ethnicity (adjusted odds ratio, 6.1); prophylaxis according to the recommended protocol not given (adjusted odds ratio, 2.4); and opening of a colostomy as the specific operation (adjusted odds ratio, 2.3). Of all the variables analyzed, more than one operation during an admission was consistently associated with the highest risk of infection in patients who had cardiac and neurosurgery as well as colon surgery. On the other hand, a traditional risk factor, e.g., the presence of drains at the site of the operation, was not found to be independently associated with an increased risk of infection in any of the groups tested. This type of analysis is essential to facilitate the introduction of a more meaningful program for intervention based on proved rather than hypothetical risk factors