The scientific basis for using surveillance and risk factor data to reduce nosocomial infection rates.

Research over the past 20 years has demonstrated that an active programme of surveillance with feedback of surgical wound infection rates to surgeons can reduce subsequent rates by 30-40%. For surveillance data and feedback to be meaningful and influential, however, certain rigorous methodological principles must be observed. First, surveillance data must be collected in an accurate, efficient and confidential manner. This requires written definitions of infection, regular clinical case-finding, post-discharge follow up for short-staying patients, and computer storage, analysis and reporting of the data in coded form that does not publicly identify individuals. Second, the variation in intrinsic risk of the patients of the various surgeons must be controlled for by stratifying the final infection rates on a multivariate risk index, which combines the traditional classes of wound contamination with measures of intrinsic patient susceptibility. This can be accomplished with a relatively small commitment of time by the Infection Control Nurse with the aid of sophisticated computer software that is now available.