THE INFLUENCE OF SURVEILLANCE METHODS ON SURGICAL-WOUND INFECTION-RATES IN A TERTIARY CARE SPINAL SURGERY SERVICE

Study Design. A 1-year prospective study of the influence of surveilla nce methods on the surgical wound infection rates in a tertiary care s pinal surgery unit. Objectives. To assess the effect of postdischarge surveillance, the diagnostic indications for surgery, and the type of procedure on the surgical wound infection rates, Summary of Background Data. Use of the National Nosocomial Infection Surveillance system fo r surgical wound infection resulted in infection rates above the publi shed values for procedures performed by the Spinal Surgical Service. A preliminary review failed to find causes for these higher rates, and a study was undertaken to assess the influence of the surveillance met hods used. Methods. Patient information collected by the Spinal Surgic al Service and surveillance data obtained by infection control were co mbined in a relational database. Surveillance after discharge was perf ormed by regularly sending questionnaires to surgeons' offices. The di agnostic indications were assessed by dividing all patients into three groups: Class D (disc disease or spinal stenosis), Class T (spinal tr auma within 60 days), and Class M (mostly complex spinal procedures fo r deformity and instability). infection rates for the three diagnostic indication classes and for procedures with and without instrumentatio n were calculated. Results. Postdischarge surveillance significantly i ncreased the infection rates, mostly by detecting superficial infectio ns that did not require readmission. Significant differences were note d between Class T and Class WI patients undergoing lumbar posterior se gmental instrumentation, despite the fact that they had a similar inci dence of risk factors according to the National Nosocomial Infection S urveillance system. The surgical wound infection rates of the National Nosocomial Infection Surveillance system may not be appropriate stand ards for specialized units with a high incidence of complex clinical p roblems and complicated surgical procedures. Conclusions. Postdischarg e surveillance, surgical procedure classification methods, and the ind ications for surgery (e.g., trauma, congenital deformity) influence th e surgical wound infection rate. Current adjustments for some of these factors in the National Nosocomial Infection Surveillance system appe ar to be inadequate when used in a tertiary care facility.