In the lowest annual jump in 20 years, national spending for health rose 9.1 percent to $387.4 billion last year, Health and Human Services Secretary Margaret M. Heckler announced yesterday.

The new figures reflect a remarkable change in the past several years. Only a few years ago, the annual rise in health costs, which reached 15.3 percent in 1980 and 15.2 percent in 1981, was one of the nation's major financial problems.

Hospital costs, particularly, were gobbling up an ever-larger share of American incomes.

However, in the past few years this has slowed -- whether permanently or not is uncertain -- and the rate of increase in 1984 dropped below double digits for the first time since 1965.

The report released by Heckler yesterday said a large part of the explanation for the change is the slowdown in the general rate of inflation but added that "other more fundamental changes have occurred in the delivery of services and in the financing of care."

Past jumps in health-care costs "caused increasing cost-consciousness on the part of consumers, employers and government" and resulted in a large number of actions now paying off in a slowdown of health-cost growth, the report said. Among them were:

* A rise of efficient prepaid health maintenance organizations, in which the enrollee receives services for a fixed annual fee.

At the end of last year, 17 million were enrolled, double the number of six years ago.

* A shift from high-cost hospital treatment to lower-cost alternative treatment -- such as outpatient surgery centers or treatment in the patient's home, the report said.

* A new round of pressure from business (which pays about $100 billion in annual health insurance premiums) and community coalitions to urge hospitals and insurers to restrain costs.

* Institution of the prospective payment system for Medicare in 1983, in which the government pays hospitals a fixed fee per stay for Medicare patients.

The system gives hospitals little incentive to hold patients and pile on tests to collect more money. Average hospital stays in 1984 for those age 65 and over dropped 7.5 percent.

The $387.4 billion total spending included $158 billion for hospitals, $75.4 billion for doctors, $25 billion for dentists, $25.8 billion for drugs and sundries, $32 billion for nursing home care, $7.4 billion for eyeglasses and appliances, $19 billion for various costs in administering programs or the net costs of health insurance, $10.7 billion for public health, $6.8 billion for noncommercial research (four-fifths by the National Institutes of Health) and $9 billion for construction of health facilities.

Although outlays overall grew 9.1 percent over the 1983 total of $355.1 billion, dental spending grew faster, 15 percent, as did spending for doctors, 10.2 percent, and spending for drugs, 9.4 percent.

However, spending for hospital services, by far the biggest single item, grew only 6.1 percent and for nursing homes only 8.9 percent. The big slowdown in hospital spending reflected reductions in admissions and days per stay.

Even so, community hospitals made record profits, $8.3 billion, up 27.6 percent.

Overall, health spending per person was $1,580, $119 over the previous year.

Of the $387.4 billion, $341.8 billion was spent for personal health care, which does not include the $45 billion spent for research, administration and insurance balances, public health and construction.

Of the personal health care costs, patients paid $95.4 billion out of pocket (28 percent); private health insurance $107.2 billion (31 percent); the federal government $101 billion (30 percent), with Medicare paying $63 billion of that and Medicaid $19.7 billion; and state and local governments paying $34.3 billion (10 percent).

The report said that as a percent of gross national product, health costs were 6.1 percent in 1965, rose to an all-time high of 10.7 percent in 1983 but dropped last year to 10.6 percent, partly because of the relatively slow rise in health costs and partly because GNP was growing rapidly.