The subheadline of the UPI article "Business Warned of AIDS Costs" {Business, Nov. 15} incorrectly stated, "Expenses Could Quadruple by 1990," a statement that was repeated twice in the text of the article but remains unsubstantiated by the facts. The statement that "health-care benefit costs could nearly quadruple by 1990" is extremely misleading, implying that the costs of AIDS will take four-fifths of national health costs, which, if true, would cripple our nation's health-care system.

The article correctly states that expected costs of treatment of AIDS patients, for the entire country, are predicted to be "$4.6 billion to $12.4 billion" in 1992. These figures are based on the projected number of AIDS cases and the cost of caring for each case.

However, the current national expenditures for health are $460 billion, making this quadrupling mathematically impossible. A prior report in The Post also belies this "new math." Using the higher of the two figures ($13 billion), with adjustment for inflation in health-care costs, Uwe Reinhardt, a noted health economist, in the Oct. 13 Health Section, calculated that the cost of AIDS in 1991 will be "1.75 percent of total national health expenditures."

So, while the costs will rise and could be a problem if planning is not started immediately, the cost of AIDS will not be the catastrophe that the headline suggested.