The percentage of HIV patients taking antiretroviral drugs who experienced the full benefit of the drugs jumped from 45 percent of 72 percent during the past decade, a figure that is lower than previous estimates. The findings, considered important for HIV prevention efforts since patients whose virus is in tight control are less likely to transmit the infection to others, are published this week in JAMA by a team of researchers led by the Perelman School of Medicine at the University of Pennsylvania and Johns Hopkins University School of Medicine. The issue's publication coincides with AIDS 2012, the annual international AIDS conference, being held in the United States for the first in over 20 years this week in Washington, D.C.

The researchers analyzed 32,483 HIV-infected patients cared for in 12 clinics across the United States between 2001 and 2010. During that time, the percentage of patients taking antiretroviral drugs who exhibited sustained viral suppression – having no detectable HIV virus in the blood every time the virus is measured -- increased from 45 percent to 72 percent. The authors point to new drugs and fixed dose combination tablets as factors in improving the efficacy and safety of antiretroviral drug regimens, as well as decreased side effects that make patients more likely to adhere to their treatment. Better access to care during this time period may also be a contributor to the improved viral suppression rates observed in the study.

Despite this increase, the number of patients with tightly controlled HIV infection was significantly less than the 77 percent to 87 percent figures reported in prior studies, which were based on one-time only measures of HIV virus in the blood, rather than considering every time the virus was measured. According to the study's lead investigator, Baligh Yehia, MD, MSHP, MPP, a fellow in the division of Infectious Diseases at Penn Medicine and HIV specialist, "if the HIV virus is not fully suppressed, individuals are at risk of transmitting HIV to others in the community." Yehia says that while significant advances in HIV therapy have occurred over the past decade, consistent adherence to medicines and outpatient care remains a major hurdle for many people living with HIV. The findings come on the heels of the Food and Drug Administration's approval this month of the first drug to prevent HIV infection. Similar to people living with HIV, healthy individuals without HIV infection who chose to take this preventative medication need to have strict drug adherence and frequent HIV testing in order to achieve benefit.