Comparison of postoperative surgical wound infection rates between institutions and over time is only valid if standard, valid and reliable definitions are used. The aim of this review was to assess evidence of validity and reliability of the definition and measurement of surgical wound infection. A systematic review was undertaken of prospective studies of surgical wound infection published over a seven-year period; 1993-1999. The information extracted from individual studies included: definition of surgical wound infection; details of wound assessment scale, scoring or grading scale systems; and evidence of assessment of validity, reliability and feasibility of identified definitions and grading systems. Two independent reviewers appraised 112 prospective studies, 90 of which were eligible for inclusion; eight studies assessed validity and/or reliability. Forty-one different definitions of surgical wound infection were identified, five of which were 'standard' definitions proposed by multi-disciplinary groups. Presence of pus was the most frequently used single component of any definition; the CDC definitions of 1988 and 1992 were the most widely implemented standard definitions; and the ASEPSIS wound assessment scale was the most frequently used quantitative grading tool. Only two formal validations of a definition were found, and six studies of reliability. This review highlights the extent of variation in definition of surgical wound infection used in clinical practice, and the need for validation of both content and organization of a surveillance system. However, realistically, there will have to be a balance between the quality of the measurement and the practicality of surveillance.
Copyright 2001 The Hospital Infection Society.