The deductible is not a natural feature of health insurance. It is an engineering choice — a deliberate design decision made by actuaries and product managers whose job is to reduce the amount insurers pay out in claims. So is the coinsurance rate, the out-of-pocket maximum, the tiered drug formulary, and the requirement to use in-network providers. Each of these features has a clinical-sounding rationale. Each of them also produces the same financial result: patients pay more and insurers pay less.
The insurance industry frames high-deductible benefit design as a consumer empowerment tool — “skin in the game,” in the industry’s preferred phrase, that aligns patient incentives with cost-conscious healthcare consumption. The evidence does not support that framing. Patients facing cost exposure do not make careful, informed decisions about which care is necessary and which is not. They defer care. They defer necessary care and unnecessary care in roughly equal measure, because the deductible does not distinguish between the two and most patients lack the clinical knowledge to make that distinction reliably on their own.
Benefit design that deters care indiscriminately is not a clinical tool. It is a cost-shifting tool. The distinction matters because the industry’s justification for high-deductible design rests entirely on the clinical framing. When that framing is tested against the evidence, it does not hold.
What the Research Shows
The relationship between cost-sharing and care utilization has been studied more rigorously than almost any other question in health economics. The foundational study is the RAND Health Insurance Experiment, conducted between 1971 and 1982 — one of the largest and most methodologically rigorous randomized controlled trials in social science history. RAND assigned participants randomly to health plans with varying levels of cost-sharing, from free care to plans requiring 95 percent coinsurance up to an annual cap.
The findings were unambiguous on one point: cost-sharing reduces utilization. Participants in high-cost-sharing plans used significantly less care than participants in free-care plans. The insurance industry has cited this finding consistently for fifty years as evidence that cost-sharing produces appropriate utilization discipline.
What the industry cites less frequently is the second major finding: cost-sharing reduced necessary and unnecessary care in roughly equal proportions. Participants in high-cost-sharing plans were less likely to receive recommended preventive care, less likely to manage chronic conditions appropriately, and — for low-income participants — showed measurably worse health outcomes than participants in free-care plans. The reduction in utilization was not targeted at waste. It was indiscriminate.
Subsequent research has confirmed and extended the RAND findings. A 2015 study published in Health Affairs examining high-deductible plan enrollment found that patients reduced both low-value care and high-value care after switching to high-deductible plans, with no evidence of selective reduction of unnecessary services. A 2021 analysis in JAMA Internal Medicine found that high-deductible plan enrollment was associated with delayed cancer diagnoses — patients deferring screening that would have detected malignancies at earlier, more treatable stages. A 2018 study in the American Journal of Public Health found that patients with diabetes in high-deductible plans were more likely to skip insulin doses due to cost than patients in lower-deductible plans, producing downstream hospitalizations that cost the system more than the insulin would have.
The evidence is consistent across study designs, populations, and time periods. High-deductible benefit design reduces claims by deterring care. It does not reliably distinguish between care that should be deferred and care that should not.
The Growth of High-Deductible Plans
The shift toward high-deductible health plans has been one of the most significant structural changes in American health insurance over the past two decades — and one of the least visible to the people it affects most.
In 2006, fewer than 10 percent of covered workers were enrolled in a plan with a deductible of $1,000 or more for individual coverage, according to the Kaiser Family Foundation’s annual employer health benefits survey. By 2023, that figure had exceeded 50 percent. The average individual deductible for covered workers in all plan types increased from $584 in 2006 to $1,735 in 2023 — a 197 percent increase in seventeen years. For workers in high-deductible plans specifically, average deductibles are substantially higher.
Over the same period, premiums continued to rise. The shift to high-deductible design did not produce lower premiums for covered workers. It produced lower claims costs for insurers — which is a different outcome entirely. Workers paying more out of pocket before coverage begins are not paying less for their insurance. They are paying the same or more for insurance that covers less of their actual care costs.
The employers who purchase coverage for their workers have driven much of this shift, often advised by the same benefits brokers and consultants whose compensation structure creates conflicts of interest documented in The Broker and Consultant Layer. Switching a workforce to a high-deductible plan reduces the employer’s premium cost — because the insurer’s claims liability decreases — but shifts the cost exposure to employees. It is a cost transfer, not a cost reduction.
Formulary Design and Drug Tiering
The tiered drug formulary is a parallel cost-shifting mechanism operating through prescription drug coverage. Insurers — working with pharmacy benefit managers, whose role in drug pricing is documented in the Prescription Drug Pricing hub — organize covered drugs into tiers that determine patient cost-sharing. Tier 1 drugs carry the lowest copayment; Tier 3 or Tier 4 drugs carry the highest, sometimes requiring coinsurance rather than a flat copayment, which can mean hundreds of dollars per prescription for specialty medications.
The clinical basis for tier placement is not transparent to patients or, in many cases, to their physicians. Formulary construction reflects negotiated rebate arrangements between PBMs and pharmaceutical manufacturers as much as it reflects clinical evidence about drug efficacy or appropriateness. A drug may be placed on a higher tier not because it is less clinically appropriate than a lower-tier alternative, but because the manufacturer offers a smaller rebate.
The practical effect for patients is predictable: when cost-sharing for a prescribed medication increases, adherence decreases. A 2010 study in the New England Journal of Medicine found that when cost-sharing for cardiovascular medications increased, adherence dropped and hospitalizations increased — at net cost to the system greater than the cost-sharing savings. As with deductible design, formulary tiering deters utilization without distinguishing between adherence that should be discouraged and adherence that is clinically essential.
Mental Health Parity and Benefit Design
The federal Mental Health Parity and Addiction Equity Act requires that insurers apply no more restrictive benefit limitations to mental health and substance use disorder coverage than to medical and surgical coverage. In practice, benefit design has been one of the primary mechanisms through which parity requirements are evaded.
Prior authorization requirements applied to mental health services at rates substantially higher than for equivalent medical services constitute a benefit design parity violation — but enforcement has been limited and the documentation burden on patients and providers is high. Cost-sharing structures that make outpatient mental health visits more expensive relative to medical visits in the same plan are another documented mechanism. The full treatment of the parity enforcement gap is in the Mental Health and Addiction hub. The connection to benefit design is direct: the tools that reduce claims across the insurance market are applied with particular force in the mental health coverage context.
The Conclusion the Evidence Supports
The insurance industry’s justification for high-deductible benefit design rests on the claim that cost exposure produces rational, informed consumption decisions that reduce waste without affecting necessary care. Fifty years of evidence, beginning with the RAND Health Insurance Experiment and extending through contemporary research on high-deductible plan enrollment, consistently refutes that claim.
Patients facing deductibles, coinsurance, and tiered formularies reduce their use of care. They do not selectively reduce unnecessary care. They reduce care — including preventive services, chronic disease management, and prescription adherence — that produces worse health outcomes when deferred or skipped. The downstream costs of that deferred care — in hospitalizations, emergency visits, and advanced-stage diagnoses — frequently exceed the claims cost that the benefit design avoided.
Benefit design that produces these outcomes is not functioning as a clinical appropriateness tool. It is functioning as a cost-shifting mechanism that transfers financial risk from insurers to patients while generating the reduction in claims that the insurer’s financial model requires. That is what the evidence shows.
Health Insurance Hub
00 — Hub: Health Insurance Industry
01 — How the Health Insurance Industry Works — and Who It Works For
02 — How Health Insurers Make Money
03 — Designed to Discourage: How Benefit Structures Reduce Claims
04 — The Denial System: How Insurers Decide What Not to Pay
05 — Prior Authorization: What Patients Experience
06 — The Administrative Burden and What It Costs
07 — Narrow Networks and What They Cost You
08 — The Employer-Sponsored Insurance Trap
09 — The Broker and Consultant Layer
10 — Billed for Diseases They Never Treated: How Medicare Advantage Fraud Works
11 — What Single-Payer Resolves: The Evidence From This Hub
12 — Health Care Forum: Join the conversation here
This article was researched and drafted with AI assistance under human review. See our full AI and editorial practices.