August 27, 2009

Tight Viral Control Is Key to Protecting Kidney Function

Strong control of HIV, whether naturally or through antiretroviral (ARV) therapy, significantly reduces the chance for decline in kidney function, according to a study published online August 25 in AIDS.

Some level of kidney disease can be found in up to 30 percent of HIV-infected people, and data clearly show a greater risk for kidney decline in people with HIV than their HIV-negative counterparts. Studies to discover the causes for this, however, have been mixed and sometimes contradictory. A handful of studies show that higher CD4 counts and lower viral load help protect kidneys. Many studies show that the loss of kidney function slows after starting HIV treatment, while other studies more clearly implicate that some or all ARVs are hard on the kidneys.

To identify the key risk factors for kidney decline, and to assess whether effective ARV therapy reduces the risk for kidney dysfunction, Andy Choi, MD, from the San Francisco Veterans Affairs Medical Center, and his colleagues examined the medical records of 615 HIV-positive participants from the Study of the Consequences Of the Protease inhibitor Era (SCOPE) cohort. Kidney function was measured by looking at the glomerular filtration rate (GFR).

Choi’s team broke the cohort down into three groups for analysis. One group included 82 people who recently started ARV therapy for the first time. A second group included people who kept viral loads below 500, but without the need for HIV treatment. A third group also maintained viral loads less than 500 copies, but were taking HIV treatment.

In the group that recently started ARV treatment, the team found that the participants on average were losing a minor to moderate degree of kidney function each year before starting treatment. After they started treatment, the decline in kidney function slowed considerably, but did not disappear.

In the two other groups of patients with low viral loads, the group controlling HIV naturally and not on ARV treatment had almost no loss of kidney function. The group on treatment, with low viral loads, had significantly more loss. However, in those not on treatment, with low viral loads, the risk of decline in kidney function did significantly increase in people who had short bursts of viral production, called “blips.”

The authors acknowledge that traditional risk factors for kidney disease, such as diabetes and race, still have a profound influence. In this study, people with the least control of HIV lost more kidney function than people with very tight viral control. The authors recommend paying careful attention to levels of virus in people on or off treatment with the aim of reducing kidney function loss.

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