Surgical Wound Misclassification

Abstract

The article “Surgical wound classifications: a multicenter evaluation” provides valuable additional evidence that the commonly used 4-level surgical wound classification (SWC) is not uniformly applied to some types of surgical procedures. Wedonot believe, however, that this observationwarrants the author’s conclusion that “Surgical wound classifications (SWC) should not be used for quality benchmarking.” Surgical wound classification is essential for benchmarking many types of quality measurements of surgical procedures. The authors demonstrated that although a high degree of rater agreement is presently achievable with class 1 (clean) operations such as inguinal hernia repairs, other types of operations, including appendectomies, have proven more challenging. As we pointed out in our article, “Inter-rater concordance of wound classifications in patients undergoing appendectomy,” low concordance rates of different observers for wound classification may be secondary to either a lack of education of the raters or a lack of clarity in the definitions of the wound classifications. We noted in our study that a literal interpretation of the SWC for appendectomies, as defined by the American College of Surgeons (ACS) and the US Centers for Disease Control (CDC), would result in every appendectomy involving acute inflammation designated as at least class 3 (contaminated). This is clearly not how appendectomies have been classified in many published studies. In an attempt to clarify SWC for operating room nurses, Devaney andRowell reported that “routine appendectomies” are class 2 (clean-contaminated), while appendectomies for “inflamed appendicitis” are class 3 (contaminated). None of our reviewers understood what the authorsmeant by “routine appendectomy” and thought the term “inflamed appendicitis” was redundant rather than explanatory. It seemed unlikely to our 4 reviewers that the risk of postoperative infections would be the same for appendectomies performed for “acute, non-purulent inflammation” and those involving “gross spillage from the gastrointestinal tract,” yet both types of cases should apparently be considered class 3. We hypothesized that raters of SWC may be confused by the wording of the definitions. Presumably the same confusion would occur in rating cholecystectomies and colon resections for diverticulitis. We note that the postoperative reviewers in the study by Levy and colleagues used a redaction of the ACSand CDC-approved SWC. It does not appear that the same redacted definitions, which were presented as an algorithm, were used by operating room nurses at the time of the operations. This may partially explain the substantial differences in classification. The authors of this study concluded, “If SWC continues to be used, individual institutions should evaluate their process of assigning SWC to ensure its accuracy and reliability.” We caution against individual hospitals undertaking a reappraisal of the wound classification definitions because the ability to compare inter-hospital quality results depends on uniformity of SWC definitions. We believe this issue is of sufficient importance to merit a collaborative study of the problem by the ACS and the CDC. We also note that “concordance” between evaluators is more appropriately presented as a kappa score than as a percentage of agreement. Kappa scores adjust for the fact that some percentage of agreement between reviewers would be expected to occur even by chance where there are only a small number of classes to choose from.