In HIV-negative people, persistent or chronic kidney disease is a risk factor for cardiovascular disease. So researchers at the Veterans Administration (VA) in the United States reviewed their large dataset containing information on more than 17,000 HIV-positive people. Their findings suggest that chronic kidney disease greatly increases the risk for heart attacks in HIV-positive people. What's more, the tests used to assess kidney health in the VA are relatively simple and routinely used across high-income countries, so the VA findings can be put into use for monitoring kidney health in other countries.
The VA database contains health-related information on more than 34,000 HIV-positive people. However, the study team focused its analysis on 17,264 people on whom they had extensive data about cardiovascular and kidney health.
The study team used two assessments of kidney health:
For the purposes of this study, the researchers classified eGFR levels as follows:
The researchers searched their database for events or outcomes such as the following, which occurred between 1999 and 2008:
In total, there were 1,194 people with reduced kidney function (eGFR less than 60). Their average profile at the start of the study was as follows:
The researchers found that, overall, the worse the health of the kidneys, the greater the chance of having serious cardiovascular disease (CVD) issues.
Taking into account many factors -- including age, pre-existing CVD risk factors, CD4+ cell count and HIV viral load -- having a low eGFR was linked to a significantly elevated relative risk for developing CVD issues as follows:
Looking specifically at eGFR and heart failure, researchers found this link:
For help in understanding relative risk please see the previous story in section B on the DAD study.
The study team found the following link between levels of albumin in the urine and a risk for heart attacks:
The team found that using both eGFR and albuminuria strengthened the predictive value of either assessment.
The findings from this VA study are important because they give doctors more tools to help identify HIV-positive patients at high risk for CVD. Furthermore, studies can now be done using eGFR and albuminuria to find ways of reducing the risk for heart attacks in people with chronic kidney disease.
The VA study may also have implications for the timing of the initiation of HAART because other research suggests that HIV can cause kidney damage. Since chronic kidney disease increases the risk for a heart attack, it may be prudent to begin HAART when CD4+ counts are higher than 350 cells. However, the issue of kidney disease and when to start HAART will require a different study.
The VA study is an observational study. Therefore, its findings need to be taken with a degree of caution. However, the link between CVD and chronic kidney disease is well established in HIV-negative people and the finding from the VA linking the same problems in HIV-positive people is not surprising.
A major weakness of this study is the very small proportion of women. The findings from this study, therefore, may not be applicable to HIV-positive women.
To accompany the publication of the VA results, infectious disease specialist Dr. Paul Sax (Harvard Medical School, Boston) wrote an editorial. He suggests that some doctors may have prescribed abacavir in place of tenofovir for their patients with kidney disease because of the risk of kidney damage from tenofovir. Because chronic kidney disease greatly increases the risk of heart attack, abacavir use in some of these people might have been mistakenly associated with heart attacks. Such a mistaken association might have occurred in DAD, in other studies or in cases where abacavir was prescribed instead of tenofovir because of pre-existing chronic kidney disease.
The findings from the VA are interesting and emphasize the need for monitoring kidney and cardiovascular health and improving the health of these organs in HIV-positive people.