Universal access to lifesaving AIDS drugs—a United Nations' Millennium Development Goal that officials hoped to accomplish by 2010—would require a daunting annual investment of $15 billion from the international community at a time when the economic downturn is hindering continued funding for relief efforts.

That's the conclusion of new analysis by researchers at the Stanford University School of Medicine, in Palo Alto, Calif. Their findings were published last month in the British Medical Journal.

The study underscores the need for groups combating AIDS to rethink how they allocate scarce resources, as what was once the centerpiece of the movement now appears to be out of reach, researchers say.

Since 2003, more than 4 million people in Africa have gained access to precious antiretroviral medications, due partly to two factors—significant declines in drug prices and a massive influx of foreign aid, they say. Drug prices have plateaued, though, in the last few years, while foreign assistance for HIV appears to be stalled amid the global economic downturn and changing global-health investment priorities.

"The things we have been doing are extraordinary in terms of reducing antiretroviral prices and mobilizing resources from the wealthy countries. Those investments have worked," says Dr. Eran Bendavid, an instructor in medicine and first author of the study. "But we're reaching the point where we can't further reduce drug costs. So it's up to the people with the purse strings to decide how close we'll get to universal access."

Universal access, the widely heralded goal of extending antiretroviral treatment to all those who need it, seems a distant possibility in today's economic climate, the researchers say. They calculate that to reach universal coverage for an additional 4.8 million patients in 13 African countries, based on today's conservative pricing of $100 a year per patient, would cost $14.8 billion a year, considering costs in addition to direct drug purchasing. Those costs include supporting clinics, staff, public health campaigns, advocacy, and paying U.S. contractors.

"We're not close to having enough resources out there for universal coverage, as the resources needed are staggering," Bendavid says.

In the study, researchers at Stanford Health Policy used publicly available data to look at the factors that made it possible to expand access to drug therapy in 13 sub-Saharan African countries. They found a direct correlation between the rise in drug availability and the substantial declines in drug prices, which fell from $1,177 to $96 a year per patient between 2003 and 2008. Those declines resulted from the introduction of generic drugs, price negotiations, bulk purchasing, trade agreements, and accommodations by U.S. pharmaceutical companies, the researchers said.

Prices, however, are unlikely to drop any further and, in fact, could increase, Bendavid noted. New guidelines from the World Health Organization recommend that patients in the developing world be put on first-line drugs that are more effective and less toxic, but that are also two to three times more expensive than existing medications, costing about $200 to $300 a year per patient, he said.

At the same time, the other major factor found to be linked directly to drug availability—foreign aid—is now on the decline. Between 2000 and 2008, total foreign assistance for HIV programs rose from a little more than $1 billion annually to around $15 billion. Such investments have had a profound impact on the lives of patients, and serve as an excellent example of how foreign aid can work effectively, Bendavid said. The researchers calculate that every additional dollar per-capita of foreign aid for HIV saved between 268,800 and 813,120 person-years.

The U.S. has provided the largest share of AIDS funding through the President's Emergency Plan for AIDS Relief, initiated in 2003 under the Bush administration. PEPFAR funding, though, has leveled off in recent years. Its annual budget for 2009 and 2010 remained the same at a little over $6 billion, while its 2011 budget reflects only a small increase, Bendavid said.

The other major supporter of AIDS programs has been the Global Fund to Fight AIDS, Tuberculosis and Malaria, a public-private partnership that recently came up short in its appeal to rich nations. The nonprofit agency had sought $20 billion in three-year pledges to expand treatment, but only received $11.7 billion in pledges, even less than what it termed its "austerity budget."

Currently, the Global Fund doesn't have enough to sustain its existing programs at a cost of $17 billion over the next three years, much less to achieve the goal of universal access by 2010—one of the U.N. Millennium Development Goals established in 2000.

"Finding ways to make those resources available is going to be a challenge for the wealthy countries unless we can reduce the prevalence of HIV substantially," Bendavid says. "It's becoming clear that providing treatment for everybody is just not sustainable."

He said the programs will have to work more efficiently in how they manage resources.

"It is somewhat sobering, but the flip side is making sure we can take the best possible care of people on treatment and make the best use of resources we have," he said.

The study was funded by the National Institute of Allergy and Infectious Diseases, the National Institute of Child Health and Human Development, and the National Institute on Aging.