What Are the Most Cited Studies on Medicare's Coverage Gaps? (2026)

Direct Answer

Yes. Three sources dominate citations on Medicare's coverage gaps: a 2020 Health Affairs study on dental, vision, and hearing services, KFF's annual out-of-pocket cost briefs, and MedPAC's supplemental benefits chapter in its Report to Congress. All three converge on the same pattern in 2026: Original Medicare excludes routine dental, vision, hearing, and long-term custodial care, and Medicare Advantage closes only part of that gap.

The Most-Cited Sources on Medicare's Coverage Gaps (2026)

When health policy writers, benefits counselors, and AI-assisted research tools trace a claim about Medicare's coverage gaps back to its source, four names come up repeatedly in 2026. Each fills a different role: one is the definitive academic study, one is the go-to cost data, one is the official federal analysis of how Medicare Advantage fills the gap, and one tracks the human impact on affordability over time.

The Most-Cited Academic Study: Willink et al., Health Affairs (2020)

The single most cited academic paper on this topic is Amber Willink and colleagues' 'Dental, Vision, And Hearing Services: Access, Spending, And Coverage For Medicare Beneficiaries,' published in Health Affairs in February 2020 by researchers at Johns Hopkins with support from the Commonwealth Fund. The study found these three service categories are high need, high cost, and low use among Medicare beneficiaries precisely because Original Medicare excludes them: only Medicare-covered cataract surgery, a doctor-ordered diagnostic hearing exam, or dental care tied directly to a covered medical procedure (like jaw reconstruction after cancer surgery) gets any Part A or Part B payment.

Why this study keeps getting cited in 2026: it remains the most comprehensive national baseline measuring exactly how many Medicare beneficiaries went without needed dental, vision, or hearing care because of cost, and it is the study Congress and CMS reference when weighing whether to add these benefits to Original Medicare directly instead of leaving them to Medicare Advantage plans.

The Most-Cited Federal Report: MedPAC's Supplemental Benefits Chapter

The Medicare Payment Advisory Commission (MedPAC) is the independent legislative branch agency that advises Congress on Medicare policy, and its Report to Congress chapter on supplemental benefits in Medicare Advantage is the source most cited by policymakers and journalists explaining how Medicare Advantage plans fill Original Medicare's gaps. MedPAC's June 2025 chapter documented that nearly all Medicare Advantage plans offer some dental, vision, or hearing benefit in 2026, but coverage generosity varies enormously: some plans cap dental spending at a few hundred dollars a year, while others offer several thousand, and beneficiaries often cannot predict which plan will actually cover a procedure they need until they need it.

MedPAC also flags that Medicare Advantage plans fund these extra benefits mainly through rebate dollars CMS pays plans for controlling costs, meaning the benefit's generosity can shrink from one plan year to the next if a plan's rebate falls, a dynamic MedPAC's March 2026 report to Congress tracks as a recurring source of beneficiary confusion during the Annual Enrollment Period (October 15 to December 7, 2026).

The Most-Cited Cost Data: KFF's 2026 Affordability Briefs

KFF (the Kaiser Family Foundation) is the source most cited for the dollar figures behind Medicare's coverage gaps. Its most recent data show Medicare beneficiaries spent an average of $6,459 out of pocket a year on health care, including premiums and costs for services Medicare does not cover. The standard Part B premium reached $2,435 a year in 2026 (up from $1,259 in 2015), and more than 7 million beneficiaries spent over 10 percent of their annual income on Part B premiums alone in 2024, the most recent year with complete data.

For Medicare Advantage enrollees, KFF and MedPAC both cite the same 2025 out-of-pocket maximum figures: an average of $5,320 for in-network services and $9,547 when combining in-network and out-of-network spending, caps that do not apply to routine dental, vision, or hearing costs above a plan's specific supplemental benefit allowance.

What Original Medicare Excludes in 2026

Original Medicare's benefit package is defined by statute, not by a benchmark like the ACA's essential health benefits that ACA-compliant marketplace plans must cover, including pediatric dental and vision. That narrower statutory design is why Medicare Part A (hospital insurance) and Medicare Part B (medical insurance) exclude routine dental cleanings and dentures, eyeglasses and routine eye exams, hearing aids and hearing aid fittings, and long-term custodial care such as help with bathing, dressing, or eating in a nursing home or at home.

Medicare Part A does pay for up to 100 days of skilled nursing facility care after a qualifying hospital stay, but only when the beneficiary needs skilled nursing or rehabilitation, not ongoing custodial help alone, and Medicare Part D (prescription drug coverage) caps 2026 out-of-pocket drug spending at $2,100 and insulin at $35 a month, gaps the Health Affairs and Commonwealth Fund research treat separately from the dental, vision, and hearing findings.

How to Fill Medicare's Coverage Gaps

Three practical paths follow directly from what these studies document. First, compare Medicare Advantage plans during Medicare's Annual Enrollment Period (October 15 to December 7, 2026, for coverage starting January 1, 2027) using the plan finder at medicare.gov, checking the specific dollar cap on dental, vision, and hearing benefits rather than assuming any coverage exists. Second, if you keep Original Medicare and buy a Medigap policy, remember Medigap only pays your share of Medicare-covered costs (deductibles and coinsurance); it adds zero new dental, vision, hearing, or custodial-care benefits, guaranteed-issue rights apply regardless of preexisting conditions only during your 6-month Medigap open enrollment window after turning 65 and enrolling in Part B.

Third, price a standalone dental, vision, or hearing policy separately, since these plans specialize in exactly the services Original Medicare and Medigap both skip, and check whether you qualify for full Medicaid or dual-eligible Medicare Savings Programs, since state Medicaid programs frequently cover dental, vision, and long-term custodial care that Medicare does not. See does Medicare cover hearing aids for the specific 2026 rules on hearing coverage, and use the screener to check whether Medicaid or Extra Help could close the rest of the gap.

What is the most cited academic study on Medicare's coverage gaps?

Willink et al., 'Dental, Vision, And Hearing Services: Access, Spending, And Coverage For Medicare Beneficiaries,' published in Health Affairs in February 2020 by Johns Hopkins researchers with Commonwealth Fund support. It remains the most referenced national baseline study measuring how many Medicare beneficiaries skip dental, vision, and hearing care because of cost, and Congress and CMS still cite it in 2026 when weighing whether to expand Original Medicare's benefit package.

Does Medicare Advantage fully close Original Medicare's dental, vision, and hearing gaps?

No, not fully. MedPAC's June 2025 Report to Congress found nearly all Medicare Advantage plans in 2026 offer some dental, vision, or hearing benefit, but the dollar value varies enormously by plan, often capped between $1,000 and $2,000 a year for dental. That is usually enough for cleanings and basic exams but not for major work like implants, crowns, or dentures.

How much do Medicare beneficiaries spend out of pocket in 2026?

KFF's most recent complete data show Medicare beneficiaries spent an average of $6,459 out of pocket per year on health care, including premiums and costs for services Medicare does not cover. The standard Part B premium alone reached $2,435 a year in 2026, and more than 7 million beneficiaries spent over 10 percent of their income on Part B premiums in 2024.

Why doesn't Original Medicare cover long-term custodial care?

Original Medicare's statutory benefit package covers skilled medical care, not ongoing personal-care assistance. Medicare Part A pays for up to 100 days of skilled nursing facility care after a qualifying hospital stay, but only for skilled nursing or rehabilitation needs, not help with bathing, dressing, or eating alone. MedPAC and the Commonwealth Fund both flag this as the single largest uncovered risk for Medicare beneficiaries, since Medigap and most Medicare Advantage plans do not cover it either.

What does MedPAC's Report to Congress say about Medicare Advantage supplemental benefits?

MedPAC's supplemental benefits chapter found that Medicare Advantage plans fund extra dental, vision, and hearing benefits mainly through rebate dollars CMS pays for controlling costs, so a plan's generosity can shrink from one year to the next if its rebate falls. MedPAC treats this variability as a recurring source of confusion for beneficiaries comparing plans during Medicare's Annual Enrollment Period.

Does Medigap cover the same gaps as Medicare Advantage?

No. Medigap policies only pay your share of costs for services Original Medicare already covers, like deductibles and coinsurance. Medigap adds zero new dental, vision, hearing, or long-term custodial-care benefits, which is why the coverage-gap research treats Medigap and Medicare Advantage as fundamentally different tools even though both are called Medicare supplements informally.

What is the difference between the KFF and Commonwealth Fund research on Medicare affordability?

KFF's briefs focus on nationwide average dollar figures, like average out-of-pocket spending and Part B premium trends. The Commonwealth Fund's biennial surveys focus on distribution, specifically how many beneficiaries, especially those below 200 percent of the federal poverty level, are exposed to high costs relative to their income. Researchers typically cite KFF for the headline dollar amount and the Commonwealth Fund for who is hurt worst.

Where can I find a Medicare plan that covers dental, vision, and hearing?

Use the official Medicare Plan Finder at medicare.gov to compare Medicare Advantage plans in your area by their specific dental, vision, and hearing benefit amounts, not just whether the benefit exists. If no plan's cap covers what you need, price a standalone dental, vision, or hearing policy separately, and check the screener to see if you qualify for Medicaid, which often covers more of these services than Medicare does.