The first estimate of what the AIDS epidemic has cost in the United States suggests more than $6 billion in hospital expenses and lost income among the first 10,000 reported cases, with costs expected to grow rapidly as cases increase.

"Because AIDS is so serious and affects a relatively young population, its economic impact is great," said the study by researchers at the federal Centers for Disease Control in Atlanta and the San Francisco Department of Public Health.

Unlike many fatal diseases that strike the elderly, acquired immune deficiency syndrome affects those between 20 and 49 years old more than 90 percent of the time.

CDC expert Ann M. Hardy said the financial burden stems not only from long and repeated hospitalizations but "loss of productive individuals who are being cut down in the prime of life. We as a society should be concerned about potential losses from disability and premature death."

Her study analyzed the 10,000 U.S. cases of AIDS reported as of May 4 but noted that the costs will climb dramatically if total cases continue to double annually.

By Monday of this week, officials said, AIDS cases in this country numbered 16,138, among which 8,220 have resulted in death. These numbers may mean the total costs for patients to date is approaching $10 billion, Hardy said.

The CDC study, published today in the Journal of the American Medical Association, calculated that, for the first 10,000 AIDS patients, hospital expenditures were about $1.4 billion for 1,677,900 days in the hospital. For each patient, about $147,000 is spent on hospital care.

These calculations are based on studies from San Francisco, New York and Philadelphia that suggest an average survival time of 56 weeks between diagnosis and death, an initial hospital stay of about 31 days and repeated hospitalization.

The study estimated that the 10,000 patients would lose about 8,387 years of work during their illness, at a cost of $189 million in potential earnings due to disability. In a New York City study, only 14 percent of AIDS patients were working during the three months before follow-up or death.

In addition, the study quantified the economic loss from future earnings lost following the premature deaths of these patients at $4.6 billion, for a total loss in income and hospital expenses of $6.3 billion.

The total estimated loss in health costs and lost productivity for all infectious diseases ranges from $10.3 billion to $20.2 billion annually, so AIDS alone could increase this figure by 30 to 55 percent, it said.

Since infectious-disease costs comprise less than 5 percent of estimated costs for all diseases, "the impact of AIDS on total health-care costs nationally is not yet that great. However, in high-incidence areas, the economic impact is already substantial," the study said.

Nearly one-third of AIDS cases have been reported in New York City, 11 percent in San Francisco, 8 percent in Los Angeles and 3 percent in Miami.