HIV and the Kidneys -- A Look Over Time

To get an idea of what effect HIV infection has on the kidneys, researchers in the United States and European Union have been conducting studies. One American study is called FRAM -- Fat Redistribution and Metabolic change in HIV infection. Researchers with this study have been monitoring the health of HIV positive and HIV negative people for several years. During this time, study participants have physical examinations, blood tests, X-ray scans and so on.

A recent analysis of the FRAM database focused on the relationship between kidney health and HIV viral load. The findings suggest that HIV infection can degrade the kidneys and that reducing viral load as much as possible helps to improve kidney health.

Study Details

The study team compared health-related information collected over five years on 337 HIV positive people and 230 HIV negative people. Our report will focus on the changes in HIV positive people.

At the start of the study, the average profile of participants was as follows:

• 32% female, 68% male
• CD4+ count -- 400 cells
• 45% had an undetectable viral load
• 88% were taking HAART
• 43% smoked tobacco
• estimated glomerular filtration rate (eGFR) -- 87

Major ethno-racial groups were as follows:

• White -- 48%
• Black -- 42%

Calculating the eGFR

For this study, the researchers based their eGFR calculations on levels of a protein found in the blood -- cystatin C. Much more detailed information on cystatin C appears later in this issue of TreatmentUpdate.

Results

Over a period of five years HIV positive people had major changes in eGFR, with some people improving and others declining.

The only factor linked to improved eGFR was a decrease in viral load as a result of participants taking highly active antiretroviral therapy (HAART).

This finding suggests that HIV is the chief cause of kidney-related problems in people with this infection. Also, the study shows that kidney health can improve when people begin to take HAART.

Researchers with FRAM found that several other factors could also lead to declining kidney health, as follows:

• chronic inflammation
• higher-than-normal blood pressure
• pre-diabetes and diabetes
• less-than-normal levels of good cholesterol -- HDL
• higher-than-normal levels of bad cholesterol -- LDL

The study team found a trend: Participants who used a class of lipid-lowering medications called fibrates seemed to have modestly declining eGFR results. The researchers suggest that this relationship be explored in another study designed for this purpose.

In contrast, participants who took medicines to lower their blood pressure had improved eGFR results. This finding underscores the wellestablished link between high blood pressure and kidney health.

Although not statistically significant, there were also trends suggesting that hepatitis C infection and heroin use were linked to gradually declining kidney health.

Anti-HIV Drugs

Two anti-HIV drugs are generally thought to have the potential to cause kidney damage -- indinavir (Crixivan) and tenofovir (Viread). In high-income countries, indinavir is seldom prescribed anymore. However, tenofovir is a widely prescribed drug. Despite its wide use in the FRAM study, tenofovir exposure was not linked to declining kidney health.

People who used the anti-HIV drug saquinavir (Invirase) had modest improvements in eGFR.

The study team encourages other researchers to use eGFR and understand its relationship not only on kidney health but cardiovascular disease as well.

Reference

1. Longenecker CT, Scherzer R, Bacchetti P, et al. HIV viremia and changes in kidney function. AIDS. 2009 Jun 1; 23(9):1089-96.

Want to read more articles in the July/August 2009 issue of Treatment Update? Click here.