Highlights from the Literature 3
Risk Factors that are Associated with Outliers in Mohs Micrographic Surgery in the National Medicare Population, 2018
by Christie Regula, MD, FACMS
Physician variation exists in the mean number of stages performed per Mohs micrographic surgery case. Physicians who are outliers may be leading to a higher health care cost burden. A previous study looking at data from 2012-2014 found the only variable that was a significant risk factor for outliers in the mean stages of Mohs was practice setting, whether that be solo or group practice.1 This current study investigates whether solo practice was still significant risk factor in 2018 data and investigated the possible relevance of new variables.
This study was a retrospective analysis of 2018 Medicare claims via the publically available database – Medicare Provider Utilization and Payment Care Data - for CPT codes used for Mohs surgery (17311, 12, 13, and 14). Using this data, mean stages per case was calculated for physicians. An outlier physician was defined as a physician whose mean stages per case was greater than 2 standard deviations from the mean of the overall group.
Physician variables that were assessed in determining the outlier status were solo practice, geographic regional location of practice, physician sex, years of experience after fellowship, American College of Mohs Surgery society membership, and state cost of living. Multivariate linear regression was performed to determine which of these factors were significant risk factors for outliers.
The mean stages per Mohs case for the head, neck, hands, feet, or genitalia was 1.6 and an outlier would be 2.28 stages or above. The mean stages per case for the trunk, arms or legs was 1.3 and an outlier would be 2.02 stages or above. Physician characteristics that were found to be significant risk factors for being an outlier included being a physician in a solo practice relative to a multi-physician practice (OR 2.4), a physician who is not a member of the American College of Mohs Surgery relative to those who are members (OR 2.0), and practicing in the West, Northeast, and South relative to the Midwest (OR 7.7 for the west, OR 6.2 for the northeast, and OR 1.8 for the south).
This study identifies risk factors for being a high outlier in the mean stages per Mohs micrographic surgery case. Solo practice was significantly associated with an upper outlier status. Solo practice has also been shown to be a risk factor for poorer performance in other medical fields.2,3 It is possible that the lack of immediate peer consultation or peer benchmarks can predispose solo practice physician to become outliers. Not being an ACMS member was also related to higher odds of being an outlier. The rigorous fellowship training required to be an ACMS member and the College’s “Improving Wisely” program for quality improvement likely contribute to the separation of its members from non-members in this study. Interestingly, the mean stages per case (CPT code 17311) decreased from 1.74 in the 2012-2014 analysis1 to 1.6 in the preset analysis. While the Medicare data does provide information on the number of CPT codes billed, the authors note that it does not provide any information on disease severity or appropriateness of the surgery or stages required. While mean number of stages does not alone reflect quality of care, physicians should self-assess the number of stages per case that are essential for the proper treatment of the patient.
References:
- Krishnan K, Xu T, Hurfless S, Park A, et al. Outlier practice patterns in Mohs micrographic surgery. JAMA Dermatol 2017;153:565-70.
- Grace ES, Wenghofer EF, Korinek EJ. Predictors of physician performance on competence assessment: findings from CPEP, the center for personalized education for physicians. Acad med J Assoc Am Med Coll 2014;89:912-9.
- Ashworth M, Schofield P, Seed P, Durbaba S, et al. Identifying poorly performing general practices in England: a longitudinal study using data from the quality and outcomes framework. J Health Serv Res Pol 2011;16:21-7.