The findings arrive at a moment when health policy experts are still debating whether the ACA’s Medicaid expansion has delivered on its promise of improved care for vulnerable populations. The new analysis suggests a more complicated picture: while expansion undoubtedly extended insurance coverage to millions of previously uninsured adults, it may simultaneously have introduced financial pressures that discourage physicians from accepting Medicaid patients, potentially eroding the very access the policy was designed to enhance.

Led by Britta E. Verhey of the University of Nevada, Reno School of Medicine, with contributions from researchers at the Mayo Clinic Alix School of Medicine, Stanford University School of Medicine, and the University of California, San Francisco, the study represents the first comprehensive examination of inflation-adjusted Medicaid reimbursement trends for Mohs micrographic surgery across the United States. The research team extracted reimbursement data for a large insurance claims database, focusing specifically on the Current Procedural Terminology codes that define Mohs surgery billing. The technical framework of the analysis centered on four codes: 17311, which covers the first stage of Mohs surgery on the head, neck, hands, feet, or genitalia; 17312, which covers each additional stage in those high-risk areas; and the corresponding codes for tumors at other anatomic sites.

The methodological approach was deliberately rigorous. All reimbursement figures were adjusted for inflation and expressed in 2022 U.S. dollars, ensuring that apparent changes in payment reflected real economic shifts rather than simple currency devaluation. States were then categorized according to their Medicaid expansion status — that is, whether they had adopted the ACA’s optional expansion of Medicaid eligibility to adults with incomes up to 138 percent of the federal poverty level. Linear regression models were applied to quantify reimbursement trends over time and to test whether those trends differed significantly between expansion and non-expansion states.

The results were striking. Between 2016 and 2022, the national weighted average reimbursement for the first stage of Mohs surgery — billed under CPT code 17311 — fell by 18.33 percent in inflation-adjusted terms. Reimbursement for additional stages, billed under CPT 17312, declined even more steeply, dropping 25.52 percent over the same window. The researchers reported a p-value of 0.0182 for these trends, indicating that the declines were statistically significant rather than random fluctuation.

But the most consequential finding emerged when the data were stratified by expansion status. In states that had expanded Medicaid, reimbursement for the first stage of Mohs surgery declined by 5.71 percent between 2016 and 2022. In states that had not expanded, the same reimbursement actually increased by 5.80 percent. The difference between the two trajectories was highly significant, with a p-value of 0.00121. In other words, the direction of payment change diverged sharply depending on a state’s policy choice, with expansion states moving backward and non-expansion states moving modestly forward.

The pattern extended to procedures performed outside high-risk anatomic areas as well. Reimbursement for non-high-risk sites fell by 26.10 percent and 32.6 percent in the respective comparisons described by the study — a magnitude of decline that, the authors suggest, reflects both the baseline generosity of state fee schedules and the downward pressure exerted by newly enrolled populations. Medicaid programs, which are administered jointly by federal and state governments, set their own physician fee schedules, and these have historically lagged well behind Medicare rates. A 2025 analysis published in Health Affairs found that Medicaid physician fees continue to trail Medicare fees across broad categories of service, and the new Mohs data suggest that dermatologic surgery has not been spared from that persistent gap.

Why would expansion states experience steeper declines? The researchers point to the mechanics of how the ACA expansion reshaped state Medicaid programs. When states expanded eligibility, they absorbed large numbers of newly insured adults, many of whom previously received care through other mechanisms or went without it entirely. To accommodate this influx within constrained budgets, states often relied on lower fee schedules for the expansion population, in some cases paying rates closer to pre-expansion Medicaid levels than to commercial or Medicare benchmarks. The federal government initially covered the full cost of expansion coverage, with the federal share gradually stepping down to 90 percent, but physician payment rates remained a state-level decision — and many states kept those rates low. The result, according to the study’s authors, is a paradox: coverage expanded, but the financial incentive for surgeons to participate in Medicaid did not keep pace, and in many places actively deteriorated.

The clinical stakes of this dynamic are considerable. Mohs micrographic surgery is a technically demanding, tissue-sparing procedure in which a surgeon removes visible tumor, examines the tissue microscopically in real time, and repeats the process in stages until no cancer cells remain at the margins. Because each additional stage requires dedicated pathology preparation and interpretation by the surgeon, reimbursement scales with the number of stages — making the 25.52 percent decline in payment for additional stages particularly meaningful. Tumors requiring multiple stages tend to be larger, more aggressive, or located in cosmetically and functionally critical areas such as the face. A payment structure that increasingly penalizes these complex cases risks distorting the economics of care precisely where the clinical need is greatest.

Prior research has documented the fragility of Medicaid access in dermatologic surgery. A nationwide survey of the Mohs workforce published in Dermatologic Surgery in 2023 found that surgeons cited low reimbursement as a primary reason for limiting or declining Medicaid participation. A 2024 study presented in the Journal of the American Academy of Dermatology documented strikingly low Medicaid acceptance rates among Mohs surgeons in multi-specialty and private clinics in New York City. Other work has shown that insurance type is associated with tumor characteristics at the time of Mohs surgery, raising concerns that patients with Medicaid present with more advanced disease — a pattern consistent with delayed access to care. The new reimbursement data provide an economic explanation for these access barriers, linking them directly to the trajectory of state payment policy.

The study’s authors also situate their findings within a broader fiscal context. Dermatologic procedures have generally fared poorly under inflation adjustment: a widely cited JAMA Dermatology analysis of Medicare reimbursement from 2007 to 2021 found that inflation-adjusted payments for common dermatologic procedures declined substantially over that period. The new study extends that picture to Medicaid, the program that serves the nation’s most economically vulnerable patients, and demonstrates that the erosion is not uniform — it is concentrated where policy choices have expanded enrollment without commensurate investment in physician payment.

Access to Mohs surgery is already unevenly distributed across the country. Previous cross-sectional research published in the same journal compared U.S. counties with and without Mohs surgeons and identified significant geographic “hotspots” and gaps in service availability. Adding declining reimbursement on top of existing geographic maldistribution, the authors warn, could deepen disparities in skin cancer outcomes for rural patients, low-income patients, and residents of non-expansion and expansion states alike — though in different ways. In non-expansion states, many low-income adults remain uninsured altogether, while in expansion states, patients may hold coverage they cannot actually use because too few surgeons accept their insurance. Coverage without access, health services researchers have long argued, is a hollow guarantee.

The authors are careful to note the limitations of their analysis. The data were drawn from a proprietary insurance claims database, PearlDiver, which requires an institutional subscription and may not capture every state’s payment structure or every claims environment. Reimbursement averages at the national level can mask substantial state-to-state variation, and the study period ends in 2022, before some of the most recent policy adjustments. Because the study analyzed billing and reimbursement data rather than individual patient records, institutional review board approval was not required. The authors reported no conflicts of interest.

Still, the central message carries weight for policymakers on both sides of the expansion debate. The Affordable Care Act’s Medicaid expansion succeeded in its primary aim: extending insurance coverage to millions of adults who previously lacked it. But insurance cards alone do not perform surgery. If inflation-adjusted reimbursement continues to fall — and falls fastest in the very states that embraced expansion — the workforce of Mohs surgeons willing to treat Medicaid patients may continue to shrink, leaving newly covered patients facing the same closed doors they encountered before the ACA. The study’s authors call for attention to fee schedules as a core component of health equity policy, arguing that sustaining physician participation in Medicaid is not a luxury but a prerequisite for translating coverage into care. As skin cancer rates continue to climb in aging populations, the economics of Mohs surgery may prove to be as consequential for public health as any laboratory breakthrough.