Last week was "Cover the Uninsured Week," when health care advocates take note of the failures of the U.S. health care system. This year, the focus has been on the number of uninsured, which is high and growing rapidly: According to the Kaiser Commission on Medicaid and the Uninsured, there are now 43.3 million uninsured, about 17 percent of the non-elderly population.

Yet the recitation of these numbers is misleading if it suggests that solving the health care crisis is a simple matter of extending coverage. To some extent, both presidential campaigns have sometimes pandered to this illusion. A large chunk of Sen. John F. Kerry's $650 billion health plan, according to a recent study by health economist Kenneth Thorpe, would go to an expansion of Medicaid and State Children's Health Insurance Programs to cover more lower-income people. President Bush's policies would use tax credits to extend coverage too, albeit to people already wealthy enough to pay taxes.

Each plan has potential. But expanding coverage, whether to the middle classes or the poor, is not sufficient to fix a health care system distorted by spiraling costs and perverse financial incentives; nor, in the long run, is it possible without addressing those issues. This country has the most expensive health care system in the world, but not the healthiest population. America also has both a medical malpractice system so rigid it puts good doctors out of business, and an extraordinarily high rate of medical errors. Billing systems discourage innovation and preventive medicine, instead rewarding doctors who prescribe long hospital stays and expensive procedures.

For that reason, true reform needs to go farther. Certainly any far-reaching reform must make greater use of evidence-based medicine: Over and over, surveys show that too many doctors fail to offer their patients the most highly recommended treatment. It may be time for the federal government to play a role by collecting and publishing information or by requiring doctors and hospitals to do so.

Smarter uses of technology -- particularly computerized medical records and prescriptions, now used by only 10 percent of health care practitioners -- as well as more effective forms of preventive medicine should be encouraged by government too, as Mr. Kerry and Mr. Bush have suggested. Better information and technology will in turn facilitate the use of consumer-driven, high-deductible health packages, which encourage consumers to make better choices.

Taxes can and should be used to encourage this new type of health plan. But more generally, taxes and regulations can and should be altered to remove the bias in favor of employer-paid health care. Ultimately, the goal has to be a system that allows people to keep their insurance when they change jobs or move in and out of the labor market. Yet there are limitations on what the market can do. Eventually, the federal government will have to deal with what is perhaps the most significant statistic of all: that 20 percent of patients are responsible for 80 percent of health care costs. At some point, government will have to begin talking about national catastrophic insurance for these patients -- or the private market will soon cease to cover anyone else. There is beginning to be bipartisan agreement on this issue: Both Mr. Kerry and R. Glenn Hubbard, former chairman of President Bush's Council of Economic Advisers, have said they favor a federal plan. Private catastrophic insurance "is not well-suited to deal with the long-term chronically ill," Mr. Hubbard wrote in an article that otherwise advocated private-sector solutions.

These changes require political courage: Until now, both insurers and the government have been reluctant to publish lists of accepted practices and recommended drugs, for example, for fear of leaving out someone's beloved provider, or even being sued by a drug company. But every service that insurers are forced to cover raises the costs, pushing someone else off the insurance rolls. It's time that Americans and their political leaders recognize that there are trade-offs in health care as in everything else and start preparing themselves to make hard choices.