Chapter 1: The Demand for Medical Care#

Why might you go to the doctor when your throat feels scratchy, and skip the visit if the copay is 10? This chapter uncovers what drives our decisions to use medical care—and shows that even something as personal as our health follows predictable economic patterns.

The Big Picture#

Health care is not like buying a sandwich. Most of us don’t pay the full price out of pocket because insurance pays most of the bill. Yet the price we face still matters a lot—it shapes whether we get a checkup, fill a prescription, or head to the emergency room. This chapter explains a key idea in health economics: the demand for medical care. We’ll see how price, income, and insurance design influence the number of doctor visits, hospital stays, and emergency trips people make. By the end, you’ll understand why even small copayment changes can nudge millions of decisions, and why policymakers wrestle with the trade-off between protecting wallets and encouraging too much care.

The Demand Curve for Medical Care: Why Price Matters#

At its heart, the demand for medical care works like demand for most things: when the price you pay goes up, you tend to buy less of it. Economists capture this idea with a demand curve—a graph that shows how many visits (or pills, or procedures) people want at each possible out-of-pocket price, holding everything else constant.

Demand curve: A line showing how many doctor visits (or other services) people want at each out-of-pocket price, if nothing else changes. It slopes downward—higher price, fewer visits.

Imagine we’re looking at outpatient care—visits to a doctor’s office, a clinic, or an urgent-care center where you don’t stay overnight. If a routine visit costs you nothing, you might go ten times a year. If it costs 75, perhaps only four times. The relationship is downward-sloping: higher price, lower quantity demanded.

Why does this happen? Two forces are at work. First, as the price rises, some visits start to feel less “worth it” compared with other ways to spend your money. Second, for people with tight budgets, a higher price simply makes the visit unaffordable. Both effects push the quantity down.

A simple mental model is to think of your health as a garden. You’d water it every day if water were free. But if each watering cost $20, you’d skip some days and hope for rain. Medical care is similar: when the price is low, we use it more freely; when it’s high, we become choosier.

Of course, medical care isn’t exactly like watering a garden—it can feel essential, even life-saving. But even for “necessary” care, people respond to price. A parent might still take a child with a high fever to the doctor no matter the cost, but might think twice about a mild rash. So the demand curve isn’t flat; it still slopes down, just sometimes steeper for some types of care than others.

📝 Section Recap: The demand for outpatient care follows a downward-sloping curve: as the out-of-pocket price rises, people make fewer visits. This basic economic principle is the starting point for understanding how insurance and policy shape health care use.

How Insurance Changes the Game: Copayments and Cost-Sharing#

In most rich countries, you rarely pay the full sticker price of a doctor visit. Health insurance covers a large share, leaving you with only a fraction—often a copayment (a fixed dollar amount per visit, like $20) or coinsurance (a percentage of the total charge, like 20%). This design is called cost-sharing, because you and the insurer share the cost.

Copayment (copay): A fixed dollar amount you pay for a covered health care service, usually at the time of the visit. For example, 100 and your coinsurance is 20%, you pay $20. Cost-sharing: Any arrangement where the patient pays part of the cost, including copayments, coinsurance, and deductibles.

Cost-sharing changes the effective price you face. If a visit’s full price is 20, the price that influences your decision is 150. So cost-sharing pushes you to a point on the demand curve with a lower effective price and more visits. This is why people with generous insurance (low copays) tend to use more care than those with high-deductible plans.

But there’s a twist: insurance can also make you less sensitive to price changes. If your copay rises from 30, that’s a 50% increase in what you pay, but it’s still a small fraction of the full cost. You might barely notice. So the steepness of the demand curve—how much quantity changes when the out-of-pocket price changes—becomes a key policy question.

📝 Section Recap: Insurance lowers the out-of-pocket price patients face through copays and coinsurance, pushing them to use more care. How much people respond to these lower prices is what we measure with price sensitivity.

The RAND Health Insurance Experiment: A Landmark Study#

How much does cost-sharing really cut back on doctor visits? And does it make people sicker? The most famous evidence comes from the RAND Health Insurance Experiment (HIE), a large-scale study conducted in the United States during the 1970s and early 1980s.

Researchers randomly assigned thousands of families to different insurance plans. Some got free care (no out-of-pocket costs), while others faced varying levels of cost-sharing: 25%, 50%, or 95% coinsurance rates, with a cap on total out-of-pocket spending to protect families from very large bills. Because assignment was random, any differences in medical use could be confidently attributed to the insurance design, not to differences in health or income.

The results were striking. People in the free-care plan used about 30–40% more outpatient services (doctor visits, etc.) than those in the 95% coinsurance plan. Hospital admissions were also lower under cost-sharing, though the difference was smaller. For the average person, fewer visits didn’t make them sicker. But there was an important exception: people with low incomes and poor health to start with stayed healthier under free care, especially for conditions like high blood pressure that need regular checkups.

Here’s a simplified summary of the findings:

The RAND HIE taught us two big lessons. First, cost-sharing is a powerful lever: even modest copays reduce use. Second, the health effects of that reduction depend on who you are. For generally healthy people, fewer visits didn’t mean worse health; for vulnerable groups, free care made a real difference.

📝 Section Recap: The RAND Health Insurance Experiment showed that higher copays lead to fewer outpatient visits and hospital stays. The health impact was small for the average person but important for low-income, high-risk groups, highlighting the delicate balance in designing insurance.

Measuring Price Sensitivity: Arc Elasticity of Demand#

To compare how sensitive demand is across different types of care, economists use a tool called elasticity. Price elasticity of demand tells us the percentage change in quantity demanded when price changes by 1%.

Price elasticity of demand: A number that measures how much the quantity demanded responds to a price change. It’s the percent change in quantity divided by the percent change in price. If the absolute value is greater than 1, demand is elastic (very responsive); if less than 1, it is inelastic (not very responsive).

For medical care, we often use arc elasticity, which works well when we compare two distinct price points—like moving from free care to a 25% coinsurance plan. The formula uses the average of the two quantities and prices:

Where:

• are quantities at the two price points,
• are the out-of-pocket prices.

Using the RAND data, we can estimate arc elasticities for different services. For outpatient care, the arc elasticity tends to be around –0.2 to –0.3. That means a 10% increase in out-of-pocket price reduces outpatient visits by about 2–3%. Demand is inelastic—people still need to see the doctor, but they trim some visits.

For inpatient care (hospital stays that require at least one night), the elasticity is even smaller, often around –0.1 to –0.2. Hospital admissions are less sensitive to price because they usually involve serious conditions where the decision isn’t really optional.

Emergency department visits present a mixed picture. For truly urgent cases, demand is extremely inelastic—you go regardless of price. But for non-urgent visits that could be handled in a doctor’s office, price sensitivity can be higher, with elasticities perhaps around –0.3 to –0.5. When people face higher copays for ER visits, they sometimes shift to cheaper settings.

Why does this matter? Knowing these elasticities helps insurers set copays that discourage unnecessary use without scaring people away from needed care. It also helps governments forecast how a new policy—like introducing a small copay for the first time—would change health care spending and health outcomes.

📝 Section Recap: Arc elasticity shows how much demand responds to price changes. Outpatient care is moderately inelastic, inpatient care is even less responsive, and emergency care varies by urgency. These numbers guide the design of cost-sharing policies.

The Trade-Off: Free Care vs. Cost-Sharing#

If free care leads to more doctors’ visits but doesn’t always make people healthier, why not charge everyone a copay? The answer is a fundamental trade-off: protecting people from big bills versus preventing overuse.

Insurance exists to protect us from large, unpredictable medical bills. The more we share costs, the less protection insurance provides. A high copay might save the system money, but it also risks deterring valuable care—like a diabetic patient skipping a checkup that could prevent a costly hospitalization later. The RAND experiment showed exactly this: low-income people with chronic conditions did worse under high cost-sharing.

On the flip side, when care feels cheap at the point of use, people may consume services they don’t really need. This is a form of moral hazard—the tendency to use more care simply because you’re insured and the price to you is low.

Moral hazard (in health insurance): The change in behavior when insurance lowers the out-of-pocket cost of care, leading people to use more services than they would if they paid the full price.

Think of it like an all-you-can-eat buffet. With a fixed entry price, you might pile your plate higher than if you paid per dish. Insurance works similarly: once you’ve paid your premium, a low copay makes each visit feel cheap, so you might go for minor issues you’d otherwise ignore.

But not all extra use is wasteful. Some of those additional visits catch problems early, improve quality of life, or provide peace of mind. The policy challenge is to set cost-sharing levels that discourage low-value care while still encouraging high-value care. That’s why modern plan designs often exempt preventive services (like vaccines and cancer screenings) from copays, while charging more for specialty visits or brand-name drugs.

There’s no one-size-fits-all answer. The optimal level of cost-sharing depends on how price-responsive people are, how much financial risk they face, and society’s willingness to protect the vulnerable. The RAND experiment and decades of later research have given us a rule of thumb: modest cost-sharing can trim unnecessary use without harming health for most people, but we must shield the poor and those with chronic illnesses.

📝 Section Recap: The trade-off between free care and cost-sharing pits financial protection against the risk of overuse. Smart insurance design uses copays to reduce low-value care while removing barriers for high-value services, especially for vulnerable groups.

Summary#

We began with a simple idea: when the price of a doctor visit rises, people go less often. That downward-sloping demand curve is the bedrock of health economics. Insurance reshapes the price we face through copays and coinsurance, making care more affordable but also nudging us to use more of it. The RAND Health Insurance Experiment gave us real-world proof that cost-sharing reduces use, with health effects that depend heavily on a person’s income and health status. Arc elasticity lets us measure just how sensitive demand is for different types of care—outpatient, inpatient, emergency—and guides smart policy design. Ultimately, every health system must balance the protection that low copays provide against the risk of encouraging too much care. Getting that balance right is what this chapter is all about.