A series of studies have dispelled the notion that patients who do not take every dose of their HIV medication create a public health risk by helping to nurture drug-resistant HIV strains. Drug companies, in particular, have often argued that HIV patients in poor countries were likely to be less adherent than those in rich countries. The findings suggest that some patients who do not take all of their medicine are actually less likely to become resistant to therapy than those who are rigidly adherent.

"The relationship between adherence and resistance is more complex than we previously understood," said David Bangsberg, a clinician with the University of California-San Francisco who published a study showing that HIV patients who were having trouble subduing the virus were more likely to develop resistance to their medications if they took most of their prescribed doses. Bangsberg's study, "HIV Levels of Adherence Do Not Prevent Accumulation of HIV Drug Resistance Mutations," is published in the Sept. 5 issue of AIDS (2003;17(13):1925-1932).

Bangsberg warned, however, that his and others' findings do not mean that patients should deliberately skip doses, because the data still show that patients who adhere better to their drug regimens live longer. Rather, researchers said, the findings indicate that patients in developing countries should be given access to the most effective drugs early in their treatment, because this maximizes their chances of controlling the virus and not developing drug resistance.

"The clear message is that in the absence of complete viral suppression, the more medication you take, the more resistance you select," said Daniel Kuritzkes, director of AIDS research at Brigham and Women's Hospital in Boston. Kuritzkes coauthored an earlier study that suggested a link between less-effective therapies and resistance.

Data on patients in poor countries show that they are no less likely than those in rich countries to adhere to treatment, researchers say. "There's no evidence to suggest that adherence is more of a challenge or resistance is more of a problem in the developing world, and there is no reason to delay the roll-out of potent antiretroviral therapies in resource-poor settings," Kuritzkes said. Kuritzkes' article, "Emergence of Dual Resistance to Zidovudine and Lamivudine in HIV-1-Infected Patients Treated with Zidovudine Plus Lamivudine as Initial Therapy," appeared in the Journal of Acquired Immune Syndromes (2000;23:26-34).

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