(Bloomberg) — Aetna Inc. has agreed to reduce out-of-pocket payments for most HIV and AIDS medicines after pressure from an advocacy group, revising coverage that had some patients paying $1,000 a month for the drugs.

Before the change, Aetna put almost all HIV drugs in its highest category of cost sharing, asking patients to pay as much as half the expense of high-priced medicines, according to the AIDS Institute. The health insurer will move the drugs into a category that will charge patients $5 to $100 after deductibles are met, the nonprofit institute said Thursday. Cynthia Michener, an Aetna spokeswoman, confirmed the change.

"Aetna's announcement will help ensure that people living with HIV/AIDS throughout the country will have greater access to essential medicines at a more affordable cost," Michael Ruppal, executive director of the AIDS Institute, said in the statement. "However, there are still many other insurers who are charging patients excessive costs for their HIV medications."