Prepaid health care plans, which already have nearly 17 million members, will continue to grow rapidly in the next decade, a newly released Louis Harris survey suggests.

The plans, called health maintenance organizations (HMOs), are increasingly accepted by consumers, employers and physicians as providing satisfactory care at reduced cost, the survey found. HMO membership has risen nearly 20 percent in the last year year.

HMOs provide nearly all medical care -- including routine checkups and preventive care such as immunizations -- for a set premium paid in advance. But HMO members must use only doctors and hospitals associated with the HMO.

"We're not infallible at predicting the future," said Humphrey Taylor, president of Louis Harris and Associates. "We find that out at election time. But I have never been more certain about any prediction I've made than that HMO membership is going to grow very rapidly for the rest of this decade and into the 1990s."

The Harris report, titled "A Report Card on HMOs: 1980-1984," was commissioned by the Kaiser Family Foundation in Menlo Park, Calif., a longtime advocate of prepaid health care systems. It was the fourth Harris survey of HMOs commissioned by the Kaiser foundation in the past five years.

The Kaiser Permanente Medical Care Program, which grew out of a health plan industrialist Henry Kaiser established in 1938 for workers building the Grand Coulee Dam, is now the nation's largest private prepaid plan. It covers nearly 5 million Americans in 12 states, including 140,000 in the District, Maryland and Virginia.

The latest findings are based on telephone interviews last August, September and October with several groups: a nationwide sample of 1,004 adults; a nationwide sample of 1,004 HMO members; a sample of 230 eligible nonmembers in areas where HMOs are available; 403 company executives in areas served by HMOs; a nationwide cross-section of 501 physicians; and a sample of 171 physicians affiliated with HMOs.

HMOs will continue to grow for several reasons pointed up in the survey, Taylor said. HMOs satisfy the needs of their members better than traditional fee-for-service care does; consumers and employers increasingly recognize that HMOs can help contain health costs; employer support for HMOs is rising; and physician hostility, "which was not able to stop the rise of HMO membership in the last decade, is now declining."

One of the most striking sets of changes between the 1980 and 1984 surveys, Taylor said, is in the relative level of satisfaction among HMO members and nonmembers.

For example, 48 percent of HMO members say they are "very satisfied" with their overall health care, compared with only 34 percent of eligible nonmembers. The gap between the two groups on that question more than doubled between 1980 and 1984.

Levels of dissatisfaction were almost identical in both groups in both years.

The Harris findings tend to rebut two common criticisms of HMOs: that they delay care and limit access to a doctor. Fifty-five percent of HMO members are "very satisfied" with their ability to see a doctor whenever they need to, the survey found, compared with only 38 percent of nonmembers. And 49 percent of HMO members are satisfied with round-the-clock availability of doctors and medical care, compared with only 32 percent of nonmembers.

The percentage who say they have one personal physician is nearly the same for both groups: 51 percent of HMO members and 55 percent of nonmembers. Moreover, HMO members are less likely than nonmembers to object to seeing a doctor other than their usual physician.

The differences in satisfaction with medical costs are "enormous," Taylor said. Over 70 percent of HMO members -- more than double the percentage of nonmembers -- are "very satisfied" with their coverage of costs for minor illnesses, lab tests and doctor's visits. For major medical expenses, the percentage of "very satisfied" is 72 among HMO members and 47 among nonmembers.

HMOs, traditionally associated with union workers, are increasingly attracting nonunion, white collar workers, the survey found.

Physicians' attitudes toward HMOs have changed dramatically since 1981, the survey found, partly because more and more doctors now work with prepaid plans. The percentage of fee-for-service doctors considering affiliation with an HMO nearly doubled between 1981 and 1984. And six of 10 doctors who are not working for a prepaid health plan say they believe prepaid plans will affect their practices in the next decade.

HMOs still face considerable, if lessening, opposition from physicians. In 1984, physicians were almost evenly divided in their attitudes toward HMOs -- 50 percent favorable and 48 percent unfavorable. Three years ago, 60 percent of physicians were opposed to HMOs.

"Many of the country's physicians still have deep reservations," said Taylor, "but the trend is clear -- physicians are becoming more and more positive about prepaid plans."

The only potential threat to continued HMO growth, Taylor said, is competition from other alternatives to traditional medical care, particularly preferred provider organizations (PPOs). Employers increasingly are contracting with a specific hospital or group of doctors for care at a discount.

"If PPOs, which are off to a flying start, were to grow very fast over the next five years," Taylor said, "that would presumably slow the growth in HMOs."