Surgical wound infection surveillance: The importance of infections that develop after hospital discharge

Background: The aim of this study was to evaluate two methods of post-discharge surgical wound surveillance and to compare the incidence and outcomes of wound infections that develop prior to patients' discharge with those that develop after hospital discharge. Methods: One thousand, three hundred and sixty inpatients who underwent major elective surgery in an 800-bed teaching hospital in western Sydney between February 1996 and July 1997 were followed prospectively. Pre-discharge wound surveillance was performed by clinical assessment by an independent researcher on the fifth (or later) postoperative day. Post-discharge wound surveillance was performed by a mail out of questionnaires completed independently by patients and surgeons. Results: Overall, 138 wound infections were diagnosed (incidence 10.1%), of which fewer than one-third (n = 44) were diagnosed before discharge (average 10.4 days postoperatively) and the remainder (n = 94) after discharge (average 20.6 days postoperatively). Seven hundred and eighty-two (57.5%) post-discharge survey forms were returned by patients and 680 (50.0%) by surgeons. When forms were returned by both surgeons and patients for the same wound (641 cases), there was substantial agreement in diagnosing infection or no infection (kappa = 0.73). Conclusions: The majority of nosocomial surgical wound infections develop after the patients' discharge from hospital. A post-discharge surveillance programme including self-reporting of infections by patients and return of questionnaires by patients and surgeons is feasible in an Australian hospital setting. However, such a programme is labour and resource intensive and strategies to increase return of questionnaires are required.