Progress in surgical-site infection surveillance.

How many surgical-site infections (SSIs) occurred last year in the United States? Were there more or fewer than 5 years ago? If more, could we have done better? If fewer, could we have done better still? It has been more than 25 years since the Centers for Disease Control and Prevention’s landmark Study on the Efficacy of Nosocomial Infection Control (SENIC) provided our first truly national portrait of surveillance for SSIs.1 Among SENIC’s contributions was a robust risk index whose direct descendant we continue to use.2 A generation later, one would expect SSI surveillance methods to be well established, the epidemiology of SSIs to be well understood, and the research frontiers to be elsewhere. And yet, in this issue of Infection Control and Hospital Epidemiology new reports from three continents speak to important unmet needs.3-5 Two of these articles address postdischarge surveillance, a problem that increasingly claims our attention as the duration of postoperative hospitalization shrinks, often to zero. A consensus statement in 19926 asserted there was no validated method for conducting postdischarge surveillance, and this conclusion remains true. The current report by Avato and Lai joins those of many predecessors7-22 in noting that most infections first become manifest after discharge. This was true even though they studied coronary ar tery bypass graft surgery, a procedure whose postoperative length of stay is still measured in days rather than hours. This report illustrates the special circumstances currently required to establish an effective system, and it also indicates the magnitude of the effort. First, Avato and Lai were able to learn what the surgeons knew because they could establish ongoing coordination with the surgeons’ offices. That, in turn, was possible because these offices were located in or near the hospital, allowing ongoing communication and review of office-based medical records as necessary. Second, the hospital’s infection control department was able to make an ongoing commitment of the scarcest and most valuable of its resources, a large amount of practitioner time. If the University of Massachusetts experience is typical, then performing postdischarge surveillance for all coronary ar tery bypass surgery in the United States will absorb the fulltime effort of several hundred infection control practitioners. Comparable effort for all surgical procedures will require considerably more than the full-time effort of all current infection control professionals. Thibon and colleagues remind us that the period of postdischarge risk often lasts longer than does postoperative care. Fortunately, the biology of SSI allows us to focus on the first 30 days for procedures that don’t involve implanted prosthetic material. However, even 30 days is long, compared with the timing of follow-up office visits. So, we will need to incorporate the “when” of postdischarge surveillance into our methods and our lexicon. Survival analysis, the method adopted by the authors, is a good solution—if, as they point out, patients whose last follow-up occurs before 30 days are neither more nor less likely to experience infection during the remainder of the 30 days than patients whose last follow-up occurs at least 30 days after surgery. Is this true? We don’t know. Is it a reasonable surmise? Possibly. In any event, the authors make a strong case for describing the duration of follow-up in any report of postdischarge surveillance. The article by Russo and Spelman addresses the fact that all patients are not created equal regarding their baseline risk of infection. Our best case-mix adjuster, the National Nosocomial Infections Surveillance (NNIS) System risk index,2 achieves most of its separation through categorization of the risk associated with procedures, rather than with patients, who are classified as either “high