March 8, 2012
Patients taking tenofovir to treat HIV infection increase their risk of kidney damage by up to 34 percent every year they take the drug, according to a new study by the San Francisco VA Medical Center.
The study involved 10,841 HIV-positive men and women who initiated antiretroviral therapy from 1997 to 2007; at some point, 4,303 took tenofovir. In comparing these patients with those who had never taken tenofovir, researchers looked for three symptoms of kidney damage: protein in the urine, rapid decline in kidney function, and chronic kidney disease.
Among tenofovir users, the risk of developing one of these signs of kidney damage rose by 11 percent to 34 percent each year; their risk remained elevated even after they stopped taking it.
However, the overall risk of long-term kidney damage was fairly low. Tenofovir users had a 2 percent risk of developing chronic kidney disease after one year on the medication, compared with a 1 percent risk for nonusers.
This does not mean patients should stop taking tenofovir, said Dr. Michael Horberg, HIV/AIDS director at Kaiser Permanente. "What it does mean is you need to be monitoring these patients closely. You need to be checking kidney function, and if the signs are trending toward worsening function, consider alternatives."
Researchers who have been evaluating tenofovir to prevent HIV infection say studies so far have shown very little increased risk of kidney damage in otherwise healthy people.
"The VA study was done in HIV-positive patients, and we don't know whether the findings apply to HIV-uninfected people who are taking tenofovir for prevention," said Dr. Albert Liu, director of HIV prevention intervention studies at the San Francisco Department of Public Health. Health officials there expect to launch a project this year to offer tenofovir widely to uninfected people for HIV prevention. Liu said researchers will closely monitor its effect on kidney function.
The study, "Association of Tenofovir Exposure with Kidney Disease Risk in HIV Infection," was published online in AIDS (2012;doi:10.1097/QAD.0b013e328351f68f).