American Council of Academic Plastic Surgeons
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Assessing the validity and reliability of the Zwisch scale in plastic surgery residency
Faisal Almufarrej MD1 Laurence Lentz MD2 Nava Guillermina MD3
1The Michael and Marian Ilitch Department of Surgery, Wayne State University School of Medicine, Detroit Medical Center, Detroit, Michigan 2The Michael and Marian Ilitch Department of Surgery, Wayne State University School of Medicine, Detroit Medical Center, Detroit, Michigan 3The Michael and Marian Ilitch Department of Surgery, Wayne State University School of Medicine, Detroit Medical Center, Detroit, Michigan

Background: The Zwisch scale is well recognized as an important simple model for assessing surgical competency but has never been studied specifically in plastic surgery. We look to assess the validity and reliability of the Zwisch scale for the use in plastic surgery residency.
Methods: This study was a prospective, pilot study which occurred over a 6-month period with several attending surgeons in 3 different teaching hospitals, evaluating residents of various PGY levels performing procedures of varying complexities. Two samples were obtained. One sample, all procedures performed by a participating faculty member and a participating resident during the given period were included. The second sample, a subset of the first that included 15 procedures. The procedures were observed in person by 2 additional surgeons who rated the residentís performance using two Zwisch scores and a third surgeon validated the operative skill assessment tool- Ottawa Surgical Competency OR Evaluation (O-SCORE). All raters were blinded to each otherís rating.
Results: A total of 6 residents participated with 5 attendings, with a total number of encounters of 126 for 184 procedures. The association between the Q1 (Complexity of Procedure- Easiest, Average, Hardest) and Q2 (Zwisch Level) was estimated with Spearman correlation and tested using Chi-square test. ICC and Spearmanís rank correlation coefficient demonstrated validity of Zwisch scores in plastic surgery procedures with good reliability amongst attending surgeons with Resident self-rating decreased score reliability (ICC Without self-rating 0.817, with self-rating 0.752).
Conclusion: When comparing plastic surgery to general surgery we see more individuality among surgeons with addition of more complexity and longer operative times. This makes it more difficult to use a standard scoring system to evaluate operative skills of plastic surgery residents. We found that Zwisch scoring is valid and has good inter-rater reliability in plastic surgery. Compared to other surgical skill assessment tools, it is quick and efficient. Therefore, current research is a good steppingstone to further research with potential for developing a plastic surgery-specific, modified-Zwisch scoring system that will give excellent reliability.


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