Medical care spending by Americans is still rising far faster than the growth of the economy or the general national inflation rate, despite a decade of intense government efforts to curb health care costs.

"We have not, as a society, figured out how to constrain overall health care spending," said Dr. William L. Roper, administrator of the Medicare and Medicaid programs.

"Changes in the health care marketplace have not eliminated the fundamental cause of expenditure growth," said Judith Feder of the Georgetown University Center for Health Policy Studies.

In 1986, overall public and private health care spending rose to $458 billion, 8.4 percent more than the preceding year, even though the Consumer Price Index for the economy as a whole rose only 1.9 percent.

The increases threaten to produce an intense battle between labor and management over the costs of employe health benefits, now $100 billion a year; bankrupt the Medicare system by the turn of the century; drive up premiums (a one-third increase in Medicare premiums for 1988 has just been announced), and consume an increasing share of the nation's gross national product.

In 1965, health care spending was only 5.9 percent of the nation's gross national product, but by 1986 it had risen to 10.9 percent, and by the year 2000 it will rise to 15 percent, the highest for any developed country, according to government estimates.

The problem has produced an abundance of proposed solutions: encourage the growth of HMOs, which have lower costs than fee-for-service health care plans; control payments to doctors; limit care or ration it (in England, people over 55 generally do not receive kidney dialysis); look over doctors' shoulders carefully to make sure they are not wasting money on marginal, excessive or even worthless treatments.

In one example of such efforts, the Department of Health and Human Services, spurred by public reaction to the Medicare premium increase, is considering asking Congress to freeze Medicare rates of pay "as soon as possible" for physicians providing other than primary care services to Medicare patients, according to a memo obtained by The Washington Post.

Three years ago, Margaret M. Heckler, then-HHS secretary, declared that the Reagan administration had "broken the back of the health care inflation monster." Heckler's claim was optimistic.

According to studies by the HHS Health Care Financing Administration, total national public and private health care spending has been rising between 8 percent and 9 percent annually since then, a bit less than previously but still two to three times as much as the general inflation rate.

A small portion of the increase in medical spending each year results from population growth. But health care economists say about three-fifths of the rise results from general inflation in the economy and from medical price increases exceeding the general inflation rate. The rest comes from increases in the volume of treatments in some cases, and the use of newer and more expensive forms of treatment.

For at least a decade, curbing the rapid growth of health care spending has been one of the highest priorities of Congress and of many in the private sector. Employers now pay more than $100 billion a year for health insurance for their employes.

As a result of one Medicare change, hospitals receive a fixed payment per patient for each stay, rather than receiving extra pay for each added day and each added test, and this has helped cut growth in Medicare hospital outlays.

But the overall numbers suggest that the nation has yet to control the problem.

Gerard Anderson, director of the Center for Hospital Finance and Management at Johns Hopkins University, said that "the bottom line" in explaining why growth in health care costs has not been brought under control is that Americans "want a high level of care, and they want access to the new technologies, and they don't want to ration either services or access to new facilities."

Robert J. Rubin, former assistant HHS secretary in the Reagan administration and now senior vice president of ICF Inc., a social sciences consulting firm, said a major reason for the continuing rapid rise in medical outlays "is the continuing improvements in medical technology and care that improve patient service at a higher price.

"An example is the MRI {magnetic resonance imaging device, which uses magnetism and radio waves to look inside the human body}, which is rapidly diffusing through the country . . . and is clearly more expensive than the technologies it supplants."

Feder, in a recent study, concluded that price hikes in the per-unit costs of individual medical services and items are "the major culprit in spending growth," not increased volume of services.

One reason why medical price increases exceed the general national inflation rate, some say, is that labor costs in the health care industry are a higher proportion of costs than in other industries, and labor costs generally have risen more rapidly.

Another is that most people do not pay for health care out of their own pockets directly but are covered by insurance. "The consumer is shielded from the price through third-party insurance," Feder said, and medical service providers thus have a greater ability to raise prices.

Roper says he believes a major solution is increased use of "capitation" schemes (HMOs are one example), under which the patient pays a single annual premium to a medical or insurance group and in return gets all the necessary services, spurring service providers to hold down costs to avoid losses.

Various other strategies are also being tried, including careful review by the government and insurance companies of doctor, hospital and nursing home care to ensure that unnecessary services are avoided. Increasingly, questions have arisen about cases in which large expenses are incurred for patients who are so severely injured or ill that recovery is virtually impossible.

Rubin, who wrestled with the health care cost problem as assistant secretary, said, "It will be difficult to control the rate of rise as long as the American public is willing to pay for improvements and there is no unanimity among physicians as to how to treat certain conditions."