Surgical Site Infection (SSI) Rates in the United States, 1992–1998: The National Nosocomial Infections Surveillance System Basic SSI Risk Index

TLDR

The study examined the National Nosocomial Infections Surveillance basic risk index to predict surgical site infection risk and evaluated the impact of laparoscopic surgery on that risk. The index combines American Society of Anesthesiologists scores of 3–5, wound class, and operative duration, and the analysis assessed how laparoscopic use modifies these factors. SSI rates rose with more risk factors in 34 of 44 procedure categories, laparoscopic surgery lowered rates for cholecystectomy and colon surgery across all risk levels, reduced rates only when no other risk factors were present for appendectomy and gastric surgery, and the index proved useful for risk adjustment, though it needed modification for four procedures where laparoscopy lowered SSI risk.

Abstract

By use of the National Nosocomial Infections Surveillance (NNIS) System's surgical patient surveillance component protocol, the NNIS basic risk index was examined to predict the risk of a surgical site infection (SSI). The NNIS basic SSI risk index is composed of the following criteria: American Society of Anesthesiologists score of 3, 4, or 5; wound class; and duration of surgery. The effect when a laparoscope was used was also determined. Overall, for 34 of the 44 NNIS procedure categories, SSI rates increased significantly (P< .05) with the number of risk factors present. With regard to cholecystectomy and colon surgery, the SSI rate was significantly lower when the procedure was done laparoscopically within each risk index category. With regard to appendectomy and gastric surgery, use of a laparoscope affected SSI rates only when no other risk factors were present. The NNIS basic SSI index is useful for risk adjustment for a wide variety of procedures. For 4 operations, the use of a laparoscope lowered SSI risk, requiring modification of the NNIS basic SSI risk index.