IMPORTANCE: Outlier physician practices in health care can represent a significant burden to patients and the health system. OBJECTIVE: To study outlier physician practices in Mohs micrographic surgery (MMS) and the associated factors. DESIGN, SETTING, AND PARTICIPANTS: This retrospective analysis of publicly available Medicare Part B claims data from January 2012 to December 2014 includes all physicians who received Medicare payments for MMS from any practice performing MMS on the head and neck, genitalia, hands, and feet region of Medicare Part B patients. MAIN OUTCOMES AND MEASURES: Characteristics of outlier physicians, defined as those whose mean number of stages for MMS was 2 standard deviations greater than the mean number for all physicians billing MMS. Logistic regression was used to study the physician characteristics associated with outlier status. RESULTS: Our analysis included 2305 individual billing physicians performing MMS. The mean number of stages per MMS case for all physicians practicing from January 2012 to December 2014 was 1.74, the median was 1.69, and the range was 1.09 to 4.11. Overall, 137 physicians who perform Mohs surgery were greater than 2 standard deviations above the mean (2 standard deviations above the mean = 2.41 stages per case) in at least 1 of the 3 examined years, and 49 physicians (35.8%) were persistent high outliers in all 3 years. Persistent high outlier status was associated with performing Mohs surgery in a solo practice (odds ratio, 2.35; 95% CI, 1.25-4.35). Volume of cases per year, practice experience, and geographic location were not associated with persistent high outlier status. CONCLUSIONS AND RELEVANCE: Marked variation exists in the number of stages per case for MMS for head and neck, genitalia, hands, and feet skin cancers, which may represent an additional financial burden and unnecessary surgery on individual patients. Providing feedback to physicians may reduce unwarranted variation on this metric of quality.
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