Surgical-site infections and the NNIS SSI Risk Index: room for improvement.

Surveillance of surgical-site infections (SSI), with feedback of appropriate data to surgeons, has been shown to be an important component of strategies to reduce SSI risk. For SSIs, the traditional wound classification system, which stratifies each wound into one of four categories (clean, clean-contaminated, contaminated, and dirty-infected), has been available since 1964. Limitations of this system of risk stratification are well recognized. One of the major problems is its failure to account for the intrinsic patient risk of developing an SSI. A composite risk index that captures the joint influence of this and other risk factors is required before meaningful comparisons of SSI rates can be made among surgeons, among institutions, or across time.