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Training Level

Resident PGY 3


Henry Ford Hospital


Introduction: Wound class helps predict wound related complications and is useful for stratifying surgical site infection (SSI) reporting. Misclassification could be significant as report cards increasingly affect reimbursement and publicly reported data. We sought to evaluate misclassification among commonly performed surgeries that are defined to be clean-contaminated or higher. We hypothesized that rates of misclassification are increasing, and this increasing trend may be correlated with laparoscopic approaches. Methods: The National Surgical Quality Improvement Program (NSQIP) database was queried from 2005-2016 by CPT codes identifying common surgeries that are by definition not clean: colectomy, cholecystectomy, hysterectomy, and appendectomy. Misclassification was defined as a procedure classified as clean. Obtained information included year of surgery, pre-operative patient characteristics, intra-operative characteristics, laparoscopic vs open approach, wound complications, readmission, and mortality. Variables were compared between correctly and incorrectly classified patients. Multivariate logistic regression was performed to derive independent predictors of misclassification. Results: 1,208,544 cases were reviewed, of which 22,925 (1.90%) were misclassified as clean. There were 351,413 colectomies (16,749 laparoscopic and 58,935 open), 376,290 cholecystectomies (347,894 laparoscopic and 28,396 open), 197,879 hysterectomies (92,924 laparoscopic, 66,979 open, and 37,976 trans vaginal) and 282,962 appendectomies (8,414 perforated, 248,491 laparoscopic and 26,057 open). Misclassification was associated with the type of procedure (p<0.01). Hysterectomy was the most commonly misclassified procedure (3.11%), and colectomy the least misclassified classified (0.82%). Misclassification was higher in laparoscopic cases (1.92% vs 1.82, p<0.01). Misclassified cases increased from 2005 to 2016 (0.22% vs 3.11%, p<0.01). Misclassified patients were younger (46.7 vs 47.7 years, p<0.01) and had lower rates of HTN (27.7% vs 30.4%, p<0.01), COPD (2.0% vs 2.7%, p<0.01), smoking history (17.1% vs 18.8%, p<0.01), and steroid use (1.7% vs 3.0%, p<0.01).Post-operatively, misclassified patients had lower rates of Clavien 4 complications (1.0% vs 2.7%, p<0.01), shorter length of stay (2.2 vs 3.2 days, p<0.01), and 30-day readmission (3.7% vs 5.0%, p<0.01). The rate of any SSI is decreased in misclassified patients (1.7% vs 3.4%, p<0.01). Open hysterectomy was the most significant positive predictor for misclassification (OR 3.34, p<0.01), while open appendectomy was the most significant negative predictor (OR 0.20, p<0.01). Conclusion: Despite guidelines, there is an increasing trend of wound misclassification. Given that misclassified patients have better outcomes, misclassification may be affected by patient characteristics, operative approach, and type of procedure, rather than reflecting the true infectious burden. Further research is warranted to explore this phenomenon.

Presentation Date


Characterization of Wound Misclassification in Common Surgical Procedures