Commercial Insurer Market Power and Medicaid Managed Care Networks.

Over 70% of Medicaid beneficiaries are enrolled in Medicaid managed care (MMC). MMC provider networks therefore represent a critical determinant of access to the Medicaid program. Many MMC insurers also participate in commercial insurance markets where prices are high, and some insurers exercise considerable market power. In this paper, we examined the relationship between commercial insurer market power and MMC physician network breadth using linked national enrollment data and provider directory data. Insurers with more commercial market power had broader Medicaid physician networks. Insurers with over 30% market share had 37.3% broader Medicaid networks than insurers in the same county that had no commercial market share. These differences were driven by greater breadth among primary care providers, as well as other specialists including OB/GYNs, surgeons, neurologists, and cardiologists. Commercial insurance market power may have spillovers on access to care for MMC beneficiaries.

Composition of buprenorphine prescribing networks in Medicaid and association with quality of care.

INTRODUCTION: Despite Medicaid's outsized role in delivering and financing medications for opioid use disorder (MOUD), little is known about the extent to which buprenorphine prescriber networks vary across Medicaid health plans, and whether network characteristics affect quality of treatment received. In this observational cross-sectional study, we used 2018-2019 Medicaid claims in Oregon to assess network variation in the numbers and types of buprenorphine prescribers, as well as the association of prescriber and network characteristics with quality of care. METHODS: We describe prescribers (MD/DOs and advanced practice providers) of OUD-approved buprenorphine formulations to patients with an OUD diagnosis, across networks. For each patient who initiated buprenorphine treatment during 2018, we assigned a "usual prescriber" and assessed four measures of quality in the 180d following initiation: 1) continuous receipt of buprenorphine; 2) receipt of any behavioral health counseling services; 3) receipt of any urine drug screen; and 4) receipt of any prescription for a benzodiazepine. We used multivariable linear regressions to examine the association of prescriber and network characteristics with quality of buprenorphine care following initiation. RESULTS: We identified 645 providers who prescribed buprenorphine to 20,739 eligible Medicaid enrollees with an OUD diagnosis. The composition of buprenorphine prescriber networks varied in terms of licensing type, specialty, and panel size, with the majority of prescribers providing buprenorphine to small panels of patients. In the 180 days following initiation, a third of patients were maintained on buprenorphine; 69.9 % received behavioral health counseling; 88.4 % had a urine drug screen; and 11.3 % received a benzodiazepine prescription. In regression analyses, while no single network characteristic was associated with higher quality across all examined measures, each one unit increase in prescriber-to-enrollee ratio was associated with a 1.18 p.p. increase in the probability of continuous buprenorphine maintenance during the 180 days following initiation (95 % confidence interval = [0.21, 2.15], p = 0.017). CONCLUSIONS: Medicaid plans may be able to leverage their networks to provide higher quality care. Our findings, which should be interpreted as descriptive only, suggest that higher prescriber-to-enrollee ratio is associated with increased buprenorphine maintenance. Future research should focus on isolating the causal relationships between MOUD prescribing network design and patient outcomes.

Increases in Medicare Spending and Use after Private Equity Acquisition of Retina Practices.

PURPOSE: Private equity (PE) firms increasingly are acquiring physician practices in the United States, particularly within procedural-based specialties such as ophthalmology including retina. To date, the potential impact of ophthalmology practice acquisitions remains unknown. We evaluated the association between PE acquisition and Medicare spending and use for common retina services. DESIGN: Retrospective difference-in-differences analysis using the 20% Medicare fee-for-service claims dataset from January 1, 2015, through December 31, 2019. PARTICIPANTS: Eighty-two practices acquired by PE during the study period and matched control practices. METHODS: We used novel data on PE acquisitions of retina practices linked to the 20% sample Medicare claims data. Retina practices acquired by PE between 2016 and 2019 were matched to up to 3 non-PE (control) practices based on characteristics before acquisition. Private equity-acquired practices were compared with matched control practices through 6 quarters after acquisition using a difference-in-differences event study design. Data analyses were performed between August 2022 and April 2023. MAIN OUTCOME MEASURES: Medicare spending and use of common retina services. RESULTS: Relative to control practices, PE-acquired retina practices increased the use of higher-priced anti-vascular endothelial growth factor (VEGF) agents including aflibercept, which differentially increased by 6.5 injections (95% confidence interval, 0.4-12.5; P = 0.03) per practice-quarter, or 22% from baseline. As a result, Medicare spending on aflibercept differentially increased by $13 028 per practice-quarter, or 21%. No statistically significant differences were found in use or spending for evaluation and management visits or diagnostic imaging. CONCLUSIONS: Private equity acquisition of retina practices are associated with modest increases in the use of higher-priced anti-VEGF drugs like aflibercept, leading to higher Medicare spending. This finding highlights the need to monitor the influence of PE firms' financial incentives over clinician decision-making and the appropriateness of care, which could be swayed by strong economic incentives. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Role of Patient Sorting in Avoidable Hospital Stays in Medicare Advantage vs Traditional Medicare.

Importance: Unlike traditional Medicare (TM), Medicare Advantage (MA) plans limit in-network care to a specific network of Medicare clinicians. MA plans thus play a role in sorting patients to a subset of clinicians. It is unknown whether the performance of physicians who treat MA and TM beneficiaries is different. Objective: To examine whether avoidable hospital stay differences between MA and TM can be explained by the primary care clinicians who treat MA and TM beneficiaries. Design, Setting, and Participants: This was a cross-sectional study of a nationally representative sample of MA and TM beneficiaries in 2019 with any of 5 chronic ambulatory care-sensitive conditions (ACSCs). The relative risk (RR) of avoidable hospital stays in MA compared with TM was estimated with inverse probability of treatment-weighted Poisson regression, both without and with clinician fixed effects. The degree to which the estimated MA vs TM difference could be explained by patient sorting was calculated by comparing the 2 RR estimates. Data were analyzed between February 2022 and April 2023. Exposure: Enrollment in MA. Main Outcome and Measures: Whether a beneficiary had avoidable hospital stays in 2019 due to any of the ACSCs. Avoidable hospital stays included both hospitalizations and observation stays. Results: The study sample comprised 1 323 481 MA beneficiaries (mean [SD] age, 75.4 [7.0] years; 56.9% women; 69.3% White) and 1 965 863 TM beneficiaries (mean [SD] age, 75.9 [7.4] years; 57.1% women; 82.5% White). When controlling for the primary care clinician, the RR of avoidable hospital stays in MA vs TM changed by 2.6 percentage points (95% CI, 1.72-3.50; P < .001), suggesting that compared with TM beneficiaries, MA beneficiaries saw clinicians with lower rates of avoidable hospital stays. This effect size was statistically significant to explain the 2% lower rate of avoidable hospital stays in MA than in TM. Conclusions and Relevance: In this cross-sectional study of MA and TM beneficiaries, the lower rate of avoidable hospital stays among MA beneficiaries than TM beneficiaries was attributable to MA beneficiaries visiting clinicians with lower rates of avoidable hospital stays. The patient sorting that occurs in MA plays a critical role in the lower rates of avoidable hospital stays compared with TM.

Trends in Medicare Advantage participation among commercial insurers.

OBJECTIVES: Commercial health insurers can participate in the rapidly growing Medicare Advantage (MA) market, which may affect network formation and prices in traditional commercial insurance markets. We aim to quantify the prevalence and growth of commercial insurers participating in MA within the same state. STUDY DESIGN: Repeated cross-sectional analysis of Clarivate's Interstudy enrollment data comprising the universe of insurers in the United States from 2015 to 2021. METHODS: We calculated the share of employer-sponsored insurance (ESI) enrollees covered by an insurer offering MA in their state in 2015, 2017, 2019, and 2021. We documented this share across states, years, and the state's 2015 tercile. RESULTS: Between 2015 and 2021, the share of ESI enrollees covered by an insurer offering MA in the same state increased from 83.5% to 95.3%. This growth was concentrated in states with initially low rates in 2015 (lowest 2015 state tercile, ≤ 70.5%), in which the share grew from 47.6% to 87.9%. In 2015, 23.5% of states had a share greater than 90.0% compared with 74.5% in 2021. CONCLUSIONS: By 2021, almost all ESI enrollees were covered by insurers who participated in MA in the same state. Future research should investigate how insurer participation in MA affects network formation and prices in commercial markets.

New Opportunities to Strengthen Medicaid Managed Care Network Adequacy Standards.

This Viewpoint discusses new standards proposed by the Centers for Medicare & Medicaid Services for ensuring that Medicare managed care networks meet enrollees' needs.

Association of Medicare Program Type with Health Care Access, Utilization, and Affordability among Cancer Survivors.

BACKGROUND: The Medicare Advantage program provides care to nearly half of Medicare beneficiaries, including a rapidly growing population of cancer survivors. Despite its increased adoption, it is still unknown whether or not the program improves healthcare access, outcomes, and affordability for cancer survivors. METHODS: We performed a cross-sectional study of Medicare beneficiaries aged ≥ 65 years with a self-reported history of cancer from the 2019 National Health Interview Survey. We used multivariable logistic regression to evaluate the association between Medicare program type (Medicare Advantage vs. traditional Medicare) and measures of healthcare access, acute care utilization, and affordability. RESULTS: We identified 4451 beneficiaries with a history of cancer, corresponding to 26.6 million weighted cancer survivors in 2019. Of the beneficiaries, 35.8% were enrolled in Medicare Advantage, whereas 64.2% were enrolled in traditional Medicare. The age, sex, racial and ethnic composition, household income, primary site of cancer, and comorbidity burden of Medicare Advantage and traditional Medicare beneficiaries were similar. In the adjusted analysis, there were no differences in healthcare access or acute care utilization between traditional Medicare and Medicare Advantage beneficiaries. However, cancer survivors enrolled in Medicare Advantage were more likely to worry about (34.3% vs. 29.4%; aOR, 1.3 (95% CI, 1.1-1.5)) or have problems paying (13.6% vs. 11.1%; aOR, 1.4 (95% CI, 1.1-1.8)) medical bills. CONCLUSIONS: We found no evidence that Medicare Advantage beneficiaries with cancer had better healthcare access, affordability, or acute care utilization than traditional Medicare beneficiaries did. Furthermore, Medicare Advantage beneficiaries were more likely to report financial strain and have difficulty paying for their medical bills than were those with traditional Medicare. Despite the generous benefits and attractive incentives, Medicare Advantage plans may not be more cost-effective than traditional Medicare is for cancer survivors. Our study informs ongoing congressional deliberations to re-evaluate the role of Medicare Advantage in promoting equity among beneficiaries with cancer.

Psychiatrist Networks In Medicare Advantage Plans Are Substantially Narrower Than In Medicaid And ACA Markets.

Medicare Advantage now covers twenty-eight million older adults, many of whom have mental health needs. Enrollees are often restricted to providers who participate in a health plan's network, which may present a barrier to care. We used a novel data set linking network service areas, plans, and providers to compare psychiatrist network breadth-the percentage of providers in a given area that are considered "in network" for a plan-across Medicare Advantage, Medicaid managed care, and Affordable Care Act plan markets. We found that nearly two-thirds of psychiatrist networks in Medicare Advantage were narrow (that is, they contained fewer than 25 percent of providers in a network's service area) compared with approximately 40 percent in Medicaid managed care and Affordable Care Act plan markets. We did not observe similar differences in network breadth for primary care physicians or other physician specialists across markets. Amid efforts to strengthen network adequacy, our findings suggest that psychiatrist networks in Medicare Advantage are particularly narrow, which may disadvantage enrollees as they attempt to obtain mental health services.

Using remotely monitored patient activity patterns after hospital discharge to predict 30 day hospital readmission: a randomized trial.

Hospital readmission prediction models often perform poorly, but most only use information collected until the time of hospital discharge. In this clinical trial, we randomly assigned 500 patients discharged from hospital to home to use either a smartphone or wearable device to collect and transmit remote patient monitoring (RPM) data on activity patterns after hospital discharge. Analyses were conducted at the patient-day level using discrete-time survival analysis. Each arm was split into training and testing folds. The training set used fivefold cross-validation and then final model results are from predictions on the test set. A standard model comprised data collected up to the time of discharge including demographics, comorbidities, hospital length of stay, and vitals prior to discharge. An enhanced model consisted of the standard model plus RPM data. Traditional parametric regression models (logit and lasso) were compared to nonparametric machine learning approaches (random forest, gradient boosting, and ensemble). The main outcome was hospital readmission or death within 30 days of discharge. Prediction of 30-day hospital readmission significantly improved when including remotely-monitored patient data on activity patterns after hospital discharge and using nonparametric machine learning approaches. Wearables slightly outperformed smartphones but both had good prediction of 30-day hospital-readmission.

State Policy and the Breadth of Buprenorphine-Prescriber Networks in Medicaid Managed Care.

Provider networks in Medicaid Managed Care (MMC) play a crucial role in ensuring access to buprenorphine, a highly effective treatment for opioid use disorder. Using a difference-in-differences approach that compares network breadth across provider specialties and market segments within the same state, we investigated the association between three Medicaid policies and the breadth of MMC networks for buprenorphine prescribers: Medicaid expansion, substance use disorder (SUD) network adequacy criteria, and SUD carveouts. We found that both Medicaid expansion and SUD network adequacy criteria were associated with substantially increased breadth in buprenorphine-prescriber networks in MMC. In both cases, we found that the associations were largely driven by increases in the network breadth of primary care physician prescribers. Our findings suggest that Medicaid expansion and SUD network adequacy criteria may be effective strategies at states' disposal to improve access to buprenorphine.

Medicare advantage and dialysis facility choice.

OBJECTIVE: To compare the characteristics of dialysis facilities used by traditional Medicare (TM) and Medicare advantage (MA) enrollees with end-stage kidney disease (ESKD). DATA SOURCES: We used 20% TM claims and 100% MA encounter data from 2018 and publicly available data from the Centers for Medicare and Medicaid Services. STUDY DESIGN: We compared the characteristics of the dialysis facilities treating TM and MA patients in the same ZIP code, adjusting for patient characteristics. The outcome variables were facility ownership, distance to the facility, and several measures of facility quality. DATA COLLECTION/EXTRACTION: We identified point prevalent dialysis patients as of July 15, 2018. PRINCIPAL FINDINGS: Compared to TM patients in the same ZIP code, MA patients were 1.84 percentage points more likely to be treated at facilities owned by the largest two dialysis organizations and 1.85 percentage points less likely to be treated at an independently owned facility. MA patients went to further and lower quality facilities than TM patients in the same ZIP code. However, these differences in facility quality were modest. For example, while the mean dialysis facility mortality rate was 21.85, the difference in mortality rates at facilities treating MA and TM patients in the same ZIP code was 0.67 deaths per 100 patient-years. Similarly, MA patients went to facilities that were, on average, 0.15 miles further than TM patients in the same ZIP code. CONCLUSION: MA enrollees with ESKD were more likely than TM enrollees in the same ZIP code to use the dialysis facilities owned by the two largest chains, travel further for care, and receive care at lower quality facilities. While the magnitude of differences in facility distance and quality was modest, the direction of these results underscores the importance of monitoring dialysis network adequacy as ESKD MA enrollment continues to grow.

Physician patient sharing relationships within insurance plan networks.

OBJECTIVE: To quantify shared patient relationships between primary care physicians (PCPs) and cardiologists and oncologists and the degree to which those relationships were captured within insurance networks. DATA SOURCES: Secondary analysis of Vericred data on physician networks, CareSet data on physicians' shared Medicare patients, and insurance plan attributes from Health Insurance Compare. Data validation exercises used data from Physician Compare and IQVIA. STUDY DESIGN: Cross-sectional study of the PCP-to-specialist in-network shared patient percentage (primary outcome). We also categorized networks by insurance market segment (Medicare Advantage [MA], Medicaid managed care, small-group or individually purchased), insurance plan type, and network breadth. DATA EXTRACTION: We analyzed data on 219,982 PCPs, 29,400 cardiologists, and 22,745 oncologists who, in 2021, accepted MA (n = 941 networks), Medicaid managed care (n = 293), and individually-purchased (n = 332) and small-group (n = 501) plans. PRINCIPAL FINDINGS: Networks captured, on average, 64.6% of PCP-cardiology shared patient ties, and 61.8% of PCP-oncologist ties. Less than half of in-network ties (44.5% and 38.9%, respectively) were among physicians with a common organizational affiliation. After adjustment for network breadth, we found no evidence of differences in the shared patient percentage across insurance market segments or networks of different types (p-value >0.05 for all comparisons). An exception was among national versus local and regional networks, where we found that national plans captured fewer shared patient ties, particularly among the narrowest networks (58.4% for national networksvs. 64.7% for local and regional networks for PCP-cardiology). CONCLUSIONS: Given recent trends toward narrower networks, our findings underscore the importance of incorporating additional and nuanced measures of network composition to aid plan selection (for patients) and to guide regulatory oversight.

Comparing Medicare Advantage and Traditional Medicare Prices for Hospital Outpatient Services With Hospital Price Transparency Data.

As Medicare Advantage (MA) plans enroll an increasingly large share of Medicare beneficiaries, how much providers charge MA plans relative to Traditional Medicare (TM) has important policy implications. We used new price transparency data from hospitals-which contain the most up-to-date negotiated prices-to evaluate whether and how MA prices differed from TM for hospital outpatient services. We found that among the 1,135 hospitals in our sample, MA prices were close to TM at about half of them, but the other half reported MA prices that deviated considerably from TM, predominantly in the direction of higher rather than lower, and rural hospitals were more likely than urban ones to charge high MA markups. Our findings also suggest that hospital price transparency data hold promise for promoting price shopping among MA beneficiaries. But greater hospital compliance and more standardized reporting are necessary for the data to be a more useful tool.

Psychiatrist and Nonpsychiatrist Physician Network Breadth in Dual Eligible Special Needs Plans.

OBJECTIVE: Dual Eligible Special Needs Plans (D-SNPs) are a type of Medicare Advantage (MA) plan for individuals who have both Medicare and Medicaid coverage. The authors compared the breadths of psychiatrist and nonpsychiatrist provider networks in D-SNPs and other MA plans. METHODS: MA plan provider network data were merged with plan service areas and a nationwide provider database to form a data set with 843 observations on networks subclassified by state and network type (D-SNP or other MA) covering 42 U.S. states and Washington, D.C. Network breadth measured the in-network fraction of clinically active Medicare-accepting psychiatrists and other physician providers in the plans' service areas in each state. Regression analyses were used to compare psychiatrist and nonpsychiatrist network breadth and psychiatrist-nonpsychiatrist breadth differences between D-SNPs and other MA plans, after adjustment for state-level differences. RESULTS: Mean psychiatrist network breadth was 0.319 in D-SNPs and 0.299 in other MA plans, and nonpsychiatrist network breadth was 0.346 in D-SNPs and 0.358 in other MA plans. Psychiatrist networks were narrower than nonpsychiatrist networks (0.303 vs. 0.355, p<0.001), but mean psychiatrist network breadth did not differ between D-SNPs and other MA plans. In regression analyses, the psychiatrist-nonpsychiatrist breadth difference was smaller in D-SNPs (-0.031) than in other MA plans (-0.060) (p=0.002). CONCLUSIONS: Psychiatrist provider networks in a nationwide sample of D-SNPs had similar breadth as psychiatrist networks used in other MA plans. Special provider network adequacy requirements for psychiatrists in D-SNP networks may be worthy of further consideration given D-SNPs' disproportionate enrollment of adults with serious mental illness who have dual Medicare-Medicaid insurance coverage.

Workforce Composition In Private Equity-Acquired Versus Non-Private Equity-Acquired Physician Practices.

Despite growth in private equity (PE) acquisitions of physician practices in the US, little is known about how changes in ownership influence workforce composition. Using clinician-level data linked to practice acquisition information, we estimated changes in clinician workforce composition in PE-acquired practice sites relative to non-PE-acquired independent practice sites for dermatology, ophthalmology, and gastroenterology specialties. We calculated a clinician replacement ratio (cumulative number of entering clinicians during 2014-19 divided by the cumulative number of exiting clinicians) across 213 PE-acquired practices and 995 matched non-PE-acquired practices. Using a difference-in-differences approach, we also examined practice-level changes in yearly clinician counts at PE-acquired practices before and after acquisition compared with non-PE-acquired controls. In aggregate and across the study period, the clinician replacement ratio was higher for PE-acquired practices compared with non-PE-acquired controls (1.75 versus 1.37), as well as within each specialty and clinician type (physician versus advanced practice provider). Relative to non-PE-acquired control practices, we also found significant yearly increases in the number of advanced practice providers at PE-acquired practices after acquisition. Taken together, these findings suggest differential changes in workforce composition at PE-acquired practices, especially a shift toward advanced practice providers for care delivery.

Medicaid reimbursement rates for primary care services and behavioral health outcomes.

We study the effects of changing Medicaid reimbursement rates for primary care services on behavioral health outcomes-defined here as mental illness and substance use disorders. Medicaid enrollees are at elevated risk for these, and other, chronic conditions and are likely to have unmet treatment needs. We apply two-way fixed-effects regressions to survey data specifically designed to measure behavioral health outcomes over the period 2010-2016. We find that higher primary care reimbursement rates reduce mental illness and substance use disorders among non-elderly adult Medicaid enrollees, although we interpret findings for substance use disorders with some caution as they may be vulnerable to differential pre-trends. Overall, our findings suggest positive spillovers from a policy designed to target primary care services to behavioral health outcomes.

Characteristics of Specialty Mental Health Provider Networks in Oregon Medicaid.

OBJECTIVE: Provider networks for mental health are narrower than for other medical specialties. Providers' influence on access to care is potentially greater in Medicaid because enrollees are generally limited to contracted providers, without out-of-network options for nonemergency mental health care. The authors used claims-based metrics to examine variation in specialty mental health provider networks. METHODS: In a cross-sectional analysis of 2018 Oregon Medicaid claims data, claims from adults ages 18-64 years (N=100,515) with a psychiatric diagnosis were identified. In-network providers were identified as those associated with any medical claims filed for at least five unique Medicaid beneficiaries enrolled in a health plan (coordinated care organization [CCO]) during the study period. Specialty mental health providers were categorized as prescribers (psychiatrists and mental health nurse practitioners) and nonprescribers (therapists, counselors, clinical nurse specialists, psychologists, and social workers). Measures of network composition, provider-to-population ratio, continuity, and concentration of care were calculated at the CCO level; the correlation between these measures was estimated to describe the degree to which they capture unique dimensions of provider networks. RESULTS: Across 15 CCOs, the number of prescribing providers per 1,000 patients was relatively stable. CCOs that expanded their networks did so by increasing the number of nonprescribing providers. Moderately negative correlations were found between the nonprescriber provider-to-population ratio and proportions of visits with prescribers as well as with usual provider continuity. CONCLUSIONS: This analysis advances future research and policy applications by offering a more nuanced view of provider network measurement and describing empirical variation across networks.

Association of Private Equity Acquisition of Physician Practices With Changes in Health Care Spending and Utilization.

Importance: Private equity acquisitions of physician practices in the US have been increasing rapidly; however, the implications for health care delivery and spending are unclear. Objective: To examine changes in prices and utilization associated with private equity acquisitions of physician practices across multiple specialties. Design, Settings, and Participants: This was a difference-in-differences event study of US physician practices specialized in dermatology, gastroenterology, and ophthalmology that were acquired by private equity firms from 2016 to 2020. Within each specialty, each private equity-acquired (PE-acquired) practice was matched with as many as 5 control practices based on the preacquisition number of unique patients, encounters, risk score, share of services billed out-of-network, and spending. The PE-acquired practices were compared with matched controls through year 2 after acquisition, using a difference-in-differences event study. Data analyses were performed from March 2021 to February 2022. Exposures: Private equity acquisition of physician practices. Main Outcomes and Measures: Measures of spending and utilization, including the charge and price (amount paid) per claim, new and unique patients, and total encounters. Results: Compared with the 2874 control practices, the 578 PE-acquired physician practices exhibited an average increase of $71 (+20.2%) charged per claim (95% CI, 13.1%-27.3%; P < .001) and $23 (+11.0%) in the allowed amount per claim (95% CI, 5.6%-16.5%; P < .001). The PE-acquired practices increased their numbers of unique patients seen by 25.8% (95% CI, 15.8%-35.6%; P < .001) compared with control practices, driven by a 37.9% increase in visits by new patients (95% CI, 25.6%-50.2%; P < .001). In aggregate, their volume of encounters increased by 16.3% (95% CI, 1.0%-32.0%; P = .04) compared with the control group, with a 9.4% increase in the share of office visits for established patients that were billed as longer than 30 minutes (95% CI, 1.7%-17.0%; P = .02). No statistically significant changes in patient risk scores were found between PE-acquired practices and controls. Within specialties, we found modest differences along selected outcomes. Conclusions and Relevance: In this difference-in-differences study, private equity acquisition of physician practices in dermatology, gastroenterology, and ophthalmology were associated with differential increases in allowed amount and charges per claim, volume of encounters, and new patients seen, as well as some changes in billing and coding.