5.5 Participant Response to Health Plan Pricing
Key Takeaways
- The RAND Health Insurance Experiment established that health care demand responds to price with an arc elasticity of roughly -0.2, meaning a 10% rise in out-of-pocket price reduces spending about 2% — real, but far less elastic than ordinary consumer goods.
- Cost sharing reduces both necessary and unnecessary care roughly indiscriminately, which is the central design problem: a blunt deductible increase suppresses guideline-recommended maintenance care alongside low-value utilization.
- Research on large deductible increases found that spending reductions came overwhelmingly from reduced quantity of care rather than from members shopping for lower prices, undermining the assumption that transparency tools automatically convert cost sharing into price shopping.
- Value-Based Insurance Design (V-BID) resolves the bluntness problem by setting cost sharing inversely to clinical value — near-zero for high-value maintenance drugs and services, higher for low-value ones — and IRS Notice 2019-45 expanded the preventive-care safe harbor that lets HSA-qualified HDHPs do this pre-deductible.
- Members respond far more strongly to salient, prospective price differences such as tiered network copays and reference-based pricing than to retrospective coinsurance, because the differential is visible at the moment of choice.
Participant Response to Health Plan Pricing
Quick Answer: Health care demand is price-responsive but inelastic — the RAND Health Insurance Experiment measured an arc elasticity near -0.2. The problem is not that cost sharing fails to work; it is that it works indiscriminately, suppressing high-value and low-value care alike. Later research on large deductible increases found the savings came almost entirely from using less care, not from shopping for cheaper care. The design response is Value-Based Insurance Design and salient, prospective price signals rather than higher across-the-board cost sharing.
1. The Foundational Evidence: The RAND Health Insurance Experiment
The RAND Health Insurance Experiment (HIE), conducted from 1974 to 1982, randomly assigned families to insurance plans with coinsurance rates from 0% (free care) to 95%, subject to an income-related out-of-pocket maximum. Random assignment removed the self-selection problem that contaminates observational studies, which is why it remains the reference point in the CEBS curriculum decades later.
Its three durable findings:
- Demand responds to price, modestly. The estimated arc elasticity of demand was approximately -0.2: a 10% increase in the out-of-pocket price reduced total spending by roughly 2%. Health care is price-responsive but substantially more inelastic than ordinary consumer goods.
- Reductions come from fewer episodes, not cheaper episodes. Cost sharing mostly reduced whether people initiated care. Once treatment began, intensity was largely determined by clinicians, not by patients.
- Cost sharing did not discriminate between appropriate and inappropriate care. Participants facing cost sharing reduced highly effective care about as much as they reduced marginally useful care. For the average participant, health outcomes were largely unaffected — but for low-income participants with hypertension and other chronic conditions, cost sharing produced measurably worse control.
That third finding is the whole design problem in one sentence. A deductible is a price on everything, and members are not equipped to sort clinical value at the point of purchase.
2. The Modern Evidence: What High Deductibles Actually Do
When a large employer moves its population to a high-deductible plan, spending reliably falls in year one. The important question is through which mechanism.
Research examining a large firm's mandatory switch to a high-deductible plan found that the spending reduction was driven overwhelmingly by reduced quantity of care — including reductions in preventively valuable and clinically indicated services — rather than by members substituting toward lower-priced providers for the same service. Price shopping accounted for a small share of the savings, and members did not meaningfully increase use of the available price-comparison tools.
Why Price Shopping Underperforms
| Barrier | Explanation |
|---|---|
| Shoppable services are a minority of spend | Emergency, inpatient, and urgent care are not shoppable. Estimates of genuinely shoppable spending typically fall in the low-to-mid tens of percent of total. |
| The decision maker is often the referring clinician | Patients rarely choose the imaging center or the laboratory; the referral does. |
| Timing | Once the deductible is met, the marginal price falls to coinsurance or zero, so the incentive to shop disappears for exactly the members using the most care. |
| Cognitive cost | Comparing a hospital's facility fee, a professional fee, and an anesthesia fee for one procedure is genuinely difficult, and the effort is uncompensated. |
| Trust and quality inference | Members frequently interpret higher price as higher quality, reversing the intended response. |
Transparency in Coverage machine-readable files and the plan-level self-service price tools discussed in Section 4.4 are compliance obligations and useful raw material for the plan sponsor and its analytics vendor. They have not, on their own, turned members into effective shoppers.
3. Value-Based Insurance Design
Value-Based Insurance Design (V-BID) inverts the blunt-instrument logic: instead of pricing all services alike, cost sharing is set inversely to clinical value.
| Service Value | Cost-Sharing Design | Examples |
|---|---|---|
| High value | Zero or near-zero; often pre-deductible | Insulin and diabetic supplies, inhaled corticosteroids, statins for secondary prevention, antihypertensives, post-MI beta blockers, retinopathy screening |
| Moderate value | Standard cost sharing | Most specialist visits, routine imaging with clear indication |
| Low value | Elevated cost sharing or exclusion | Imaging for uncomplicated low back pain in the first six weeks, brand drugs with therapeutically equivalent generics, non-indicated screening |
The HSA Constraint and Its Relaxation
V-BID historically collided with IRC §223: an HSA-qualified HDHP generally may not pay for anything before the statutory minimum deductible ($1,700 self-only / $3,400 family for 2026) except preventive care. IRS Notice 2019-45 expanded the preventive-care safe harbor to include a specified list of services and drugs for individuals with certain chronic conditions — for example, insulin and glucose-lowering agents for diabetes, inhaled corticosteroids for asthma, statins for heart disease or diabetes, ACE inhibitors for congestive heart failure or diabetes, and retinopathy screening for diabetes. A plan may cover those items pre-deductible without disqualifying HSA eligibility. Separately, telehealth relief allowing pre-deductible telehealth coverage in HSA-qualified HDHPs was extended and made permanent, so plans no longer need to track a sunset date for that provision.
This is the single most exam-relevant intersection in GBA 2: a candidate who proposes zero-dollar maintenance drugs in an HDHP must be able to say why that does not blow up HSA eligibility.
4. Salience: Prospective Beats Retrospective
Members respond much more strongly to price differences that are visible at the moment of choice than to those settled afterward on an explanation of benefits.
- Tiered network copays — a $25 copay at a Tier 1 hospital versus $500 at Tier 2 — move volume, because the differential is stated, prospective, and simple.
- Reference-based pricing — the plan pays a defined reference amount (for example, for knee and hip replacement) and the member pays the excess at a higher-priced facility — produces some of the largest documented shifts in facility selection, because the consequence is concrete and disclosed in advance.
- Centers of Excellence with waived cost sharing and travel benefits convert a price signal into a positive inducement rather than a penalty, which usually generates higher member acceptance.
- Percentage coinsurance on an unknown allowed amount is the weakest signal of all: the member cannot compute the consequence in advance and therefore cannot respond to it.
Design Implications for a Benefits Committee
- Do not expect a deductible increase to produce price shopping; expect it to produce less care, some of it needed.
- Protect high-value chronic maintenance care from the deductible using the Notice 2019-45 safe harbor when the plan is HSA-qualified.
- Put the price signal where the member actually makes a choice — network tier, facility, site of care — and state it in dollars, not percentages.
- Monitor the low-income and chronic-condition subpopulations specifically after any cost-sharing increase, because the RAND findings indicate those are the members whose clinical control degrades first.
What did the RAND Health Insurance Experiment establish about the relationship between cost sharing and the clinical appropriateness of the care that members forgo?
An employer moved its entire population to a high-deductible health plan and observed a large first-year spending reduction. Research on comparable mandatory switches indicates the reduction arises primarily through which mechanism?
A plan sponsor wants its HSA-qualified high-deductible plan to cover insulin, inhaled corticosteroids for asthma, and statins for members with diabetes at zero cost sharing before the deductible is satisfied. What is the governing authority and outcome?