Medicare Radiology Group Network Market Share: Recent Characteristics and Trends
Authors: Pyrros Ayis , Fornelli Brian , Rodriguez-Fernandez Jorge Mario , Borstelmann Stephen M , Siddiqui Nasir , Galanter William 
Published: March 2023

Purpose: Recent trends in US healthcare have seen growing consolidation of healthcare providers, including radiology groups, with fewer and larger radiology groups. We assessed recent trends and characteristics in radiology group network market share (NMS) across the US among Medicare beneficiaries. Methods: Using freely available datasets CareSet DocGraph Hop Teaming, Medicare Physician Compare, and Medicare Physician and Other Supplier Public Use File (PUF), all radiologists were identified and associated to group practices annually between 2014 and 2017. Radiology groups outside the US, not present in all three databases, or with only one radiologist were excluded. The annual frequency of radiological exams performed was determined from the PUF and used to calculate the percentage of magnetic resonance and computed tomography (MR/CT) imaging performed as well as the number of beneficiaries undergoing MR/CT per radiology group. Physician referrers without evaluation and management codes for office visits in the PUF file were excluded from the DocGraph file. Provider connections were geospatially mapped and plotted. The percentage of radiology group NMS was calculated as the number of patients a group received, divided by the total number of potential and actual connections, and multiplied by 100. Univariate analysis of radiology group NMS was performed against a variety of characteristics and compared using Kruskal-Wallis and Dunn tests, as appropriate. Univariate linear regression was used to assess the association between NMS and calendar year, as well as average wait time and calendar year. Multivariate linear regression was used to model the radiology group cumulative normalized percentile NMS, with multiple predictors for the year 2017. Results: Between 2014 and 2017, 1,764 unique radiology groups were identified, representing 17,879 radiologists in 2014, 18,143 radiologists in 2015, 20,915 radiologists in 2016, and 22,187 radiologists in 2017, with an average NMS per group for 2014 of 14.8%, 2015 of 14.5%, 2016 of 13.6%, and 2017 of 13.1%, demonstrating a small but statistically significant negative trend over four years (2014-2017), with a 0.6% decrease per year (P < 0.001). Average day weight across years (2014-2017) demonstrated a slight upward trend, with a 0.3% increase per year. The yearly percentage of MR/CT studies across all groups was 24.6-26.6%, with the most performed studies being chest radiography, mammography, and CT of the head without contrast. Univariate analysis of radiology group NMS was not significantly different between academic and nonacademic groups for all years (P > 0.05) but was significantly different for radiology-only versus multispecialty groups across all years (P < 0.05). Multivariate linear regression on 2017 data demonstrated statistically significant independent negative predictors for NMS including larger group size (50-99, >=100), higher practice MR/CT imaging percentage, and South location, while the increasing log of the number of beneficiaries undergoing MR/CT was a positive predictor, with an adjusted R-squared of 0.56 (all P < 0.01). Conclusions: Among Medicare beneficiaries from 2014 to 2017, radiology group NMS (mean 14%, median 9.0%, IQR 4-19.2%), slightly decreased over time by 0.6% per year, despite occurring during a period of widespread practice consolidation. The negative predictors for NMS at the group level included larger group size, South region, increased average wait time, and higher MR/CT imaging percentage, while the positive predictor was the increased number of beneficiaries undergoing MR/CT. Of these predictors, radiology groups are most likely to increase NMS by decreasing average wait times.