Picture a site coordinator at a transplant center pulling the eligibility screen on a new ESKD referral. The patient qualifies on every clinical criterion: dialysis vintage, age, comorbidity profile, geographic proximity. Then she opens the insurance field. Medicare Advantage. She flags the record and moves on, because she already knows from the last three cycles that MA patients at her site are hitting the transplant waitlist at roughly half the rate of fee-for-service patients, and the protocol’s enrollment plan was built as if payer type does not exist.
A cohort study published in JAMA has now put numbers to what transplant coordinators have been navigating by instinct since January 2021. In the first three years after ESKD patients gained the right to enroll in Medicare Advantage under the 21st Century Cures Act, MA beneficiaries received 2.51 kidney transplants per 1,000 person-months versus 4.60 among traditional Medicare beneficiaries, a gap that survived adjustment for clinical covariates. Over that same window, MA enrollment nationally climbed from 25.8 million to 30.2 million beneficiaries, meaning the cohort generating that disparity grew by approximately 4.4 million people while the disparity persisted.
For sponsor clinical operations teams running kidney disease, transplant immunology, or dialysis-dependent chronic disease trials, this finding should land as an enrollment math problem, not a policy observation.
Payer Mix Is Now a Site Feasibility Variable
Study feasibility questionnaires ask sites about patient volume, investigator experience, staff capacity, and IRB turnaround. Almost none ask about the payer composition of the site’s ESKD population, specifically what share of eligible patients carry MA plans versus traditional Medicare. The JAMA data suggests that omission is now costing sponsors enrollment headroom they cannot see during site selection.
The mechanism behind the transplant rate gap is not fully resolved in the literature, but prior authorization is the clearest operational candidate. MA plans have broad latitude to require prior authorization for procedures that traditional Medicare covers without it, and kidney transplant workup, imaging, cardiac clearance, infectious disease panels, surgical consultation, generates exactly the kind of multi-step authorization queue that delays or derails waitlisting. CMS’s Interoperability and Prior Authorization Final Rule (CMS-0057-F) will impose new prior authorization transparency and decision-timeline requirements on MA plans starting January 2026, but that rule does nothing for the 2021–2023 enrollment cohort the JAMA study captured, and its downstream effect on transplant access timelines will take years to measure.
What that means operationally: if your trial’s primary endpoint requires a transplant event, or if waitlist placement is an eligibility criterion, your MA-insured patients face a structurally longer path to that event, independent of their clinical readiness. Sites I work with in nephrology are already seeing this play out in screen failure logs, where MA patients who meet all clinical criteria are failing screens because they cannot clear the payer-driven procedural prerequisites within the protocol’s screening window. The screen failure rate problem is downstream of a prior authorization timeline problem, and most enrollment models do not connect those two variables.
The practical consequence shows up in site startup projections. A transplant center with 60% MA penetration in its ESKD population will not perform like a center with 20% MA penetration, even if their aggregate patient volumes look identical on a feasibility questionnaire. That difference belongs in the site selection model.
What the Consent and Enrollment Workflows Actually Look Like Now
Beyond waitlist access, payer type creates a second operational wrinkle that protocol teams are underestimating: the consent and engagement workflow for MA patients diverges meaningfully from the traditional Medicare workflow, and most trial site activation packages were not written to account for it.
Traditional Medicare beneficiaries moving through a transplant trial consent process deal with one coverage framework. MA beneficiaries deal with their plan’s specific network rules, any applicable referral requirements, and plan-specific coordination of benefits language, all of which affects what the site can tell a patient about cost coverage for trial-related procedures. ICH E6(R3), section 4.8, requires that the informed consent process cover “the anticipated expenses, if any, to the subject.” When trial-related procedures intersect with MA plan benefits in ways that differ from traditional Medicare, the coordinator’s ability to give an accurate answer to that question becomes plan-dependent, and often requires a benefits verification call that adds two to five business days to the pre-consent workflow.
Sites running transplant protocols under tight screening windows, 21 or 28 days is common, absorb that delay as screening time lost. If the patient’s MA plan requires a referral authorization before the site can perform the trial-specific workup, the coordinator is now managing a parallel prior authorization track that the protocol’s operational timeline never anticipated. Across our network, the sites hitting the most severe query aging on ESKD studies are concentrated at centers with high MA enrollment, not because their data management is weaker, but because their source document timelines are stretched by payer-driven delays that EDC systems record as coordinator lag.
The counterintuitive read on this is that the 21st Century Cures Act, by giving ESKD patients access to MA plans, expanded patient choice in a way that also fragmented the operational environment for trials recruiting from that population. More plan options for patients translated into more payer pathway variability for sites, and sites absorbed that variability as operational friction without any corresponding adjustment in sponsor timelines or budgets.
What Operators Need to Change Before the Next Protocol Draft
For clinical operations teams building ESKD or transplant protocols right now, the adjustment is concrete. Add payer mix to the feasibility questionnaire, specifically, the percentage of the site’s active ESKD patients enrolled in MA plans versus traditional Medicare, and the site’s average prior authorization turnaround time for transplant workup procedures. Weight those answers in site scoring alongside patient volume. A site with 400 ESKD patients and 70% MA penetration may produce fewer enrollable subjects per quarter than a site with 250 patients and 30% MA penetration, if the trial’s eligibility or endpoint structure requires waitlist placement or transplant events.
Extend screening windows in protocols targeting ESKD populations. Twenty-eight days was the working norm when the eligible population was predominantly traditional Medicare. With MA penetration in the ESKD pool growing, 30.2 million MA enrollees nationally as of 2023, up from 25.8 million in 2021, the authorization delays that MA patients face during screening have become a population-level variable, not an edge case. A 42-day screening window with a documented payer-pathway extension provision costs almost nothing in protocol design and saves sites from protocol deviations that were created by the enrollment plan, not by the site.
For sites, the practical move is a payer-pathway SOP that runs in parallel with the standard screening SOP, a documented workflow for MA patients that initiates benefits verification and, where applicable, prior authorization requests at the moment of eligibility confirmation, not after the clinical screening battery is complete. That parallel track, built into the site’s standard operating procedure before the study opens, turns a reactive coordination problem into a scheduled workflow. The sites in our network that built this during 2022 and 2023 show meaningfully lower MA-related screen failure rates than those that treated each MA patient’s authorization process as a one-off.
Sponsors reviewing site performance data for ongoing ESKD trials should pull screen failure logs and stratify by payer type today. If MA patients are failing at materially higher rates than traditional Medicare patients on the same clinical criteria, the cause almost certainly sits in the authorization and scheduling pathway, which means the fix is operational, not a protocol amendment. But if that stratification has never been run, the enrollment shortfall looks like a site capacity problem, the sponsor adds a new site, and the new site faces the same MA-related drag on the same timeline.
The JAMA study documented a transplant access gap. What it actually handed sponsor clinical operations is a diagnostic: payer type now predicts trial engagement timelines in ESKD research, and every enrollment plan that ignores that variable is projecting into a patient population that no longer exists.
References
- JAMA, “Medicare Advantage Enrollment and Access to Kidney Transplant After the 21st Century Cures Act”
- ResearchGate, Medicare Advantage vs. Traditional Medicare kidney transplant rates: 2.51 vs. 4.60 per 1,000 person-months
- ATI Advisory, Medicare Advantage Enrollment Trends: 25.8M (2021), 28.1M (2022), 30.2M (2023)
- Elion Health, CMS Interoperability and Prior Authorization Final Rule (CMS-0057-F), effective January 2026
- ONC/HealthIT.gov, 21st Century Cures Act Information Blocking Rule applicability date: April 5, 2021
