African-Americans with HIV have higher risk of aggressive kidney disease

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HIV-infected African-Americans who develop kidney disease are more likely to have a more aggressive form of the disease than white people with HIV, say US researchers writing in the June 1st edition of the Journal of Infectious Diseases.

Chronic kidney disease, and its most serious form, end stage renal disease, are more common in HIV-infected individuals. A 2004 study using data from the US Renal Data System suggested that the risk of developing end-stage renal disease is around 50 times higher in HIV-infected African-Americans than in HIV-infected whites (Eggers and Kimmel 2004).

But because patients are enrolled on to this database when they start dialysis – or renal replacement therapy– researchers have been unsure of the effect of race on earlier stages of chronic kidney disease.

Glossary

renal

Relating to the kidneys.

end-stage disease

Final period or phase in the course of a disease leading to a person's death.

enzyme

A protein which speeds up a chemical reaction.

receptor

In cell biology, a structure on the surface of a cell (or inside a cell) that selectively receives and binds to a specific substance. There are many receptors. CD4 T cells are called that way because they have a protein called CD4 on their surface. Before entering (infecting) a CD4 T cell (that will become a “host” cell), HIV binds to the CD4 receptor and its coreceptor. 

This new study compared the incidence of chronic kidney disease and progression to end-stage renal disease in 3332 HIV-infected African-Americans with 927 HIV-infected white subjects.

The progression of the disease was monitored by measuring the glomerular filtration rate, a measure of how well the kidneys are working.

After around 4.5 years of follow-up, a total of 284 subjects developed chronic kidney disease, of whom 100 progressed to end-stage renal disease.

African-Americans were at a slightly increased risk of developing chronic kidney disease compared to whites. But once chronic kidney disease had started they went on to develop end-stage renal disease much faster than white subjects – in fact they were almost 18 times more likely to go on to need renal replacement therapy during the study period (Lucas 2008).

Correspondingly, their decline in glomerular filtration rate was six times more rapid than white subjects.

The researchers say that although there are many different types – or pathologies – of chronic renal disease in people with HIV, there is one specific type of kidney damage, termed HIV-associated nephropathy, which is more common in people of African descent and is associated with an aggressive course and rapid progression to end-stage renal disease.

They add that this study suggests the African-American/white disparities in HIV-related end stage renal disease are mostly explained by a more aggressive natural disease history and less by racial differences in the actual incidence of chronic kidney disease.

But they emphasise that the rates of chronic kidney disease dropped over the study period as HIV treatments improved. And treatment with newer antihypertensive drugs – the angiotensin converting enzyme (ACE) inhibitors and angiotensin-II-receptor blockers (ARBs) – was associated with a slower progression to end-stage renal disease.

In an accompanying editorial Dr Christina Wyatt, a nephrologist at the Mount Sinai School of Medicine in New York, warns there is a potential for an epidemic of HIV-related kidney disease and ESRD in disadvantaged minority populations and in Africa (Wyatt 2008).

She says: "The international medical community should work to develop simple, inexpensive and reliable methods to detect and manage early kidney disease in these vulnerable populations."

References

Eggers PW, Kimmel PL. Is there an epidemic of HIV infection in the US ESRD program? Journal of the American Society of Nephrology 16:2412-2420, 2004.

Lucas GM, Lau B et al. Chronic kidney disease incidence and progression to end-stage renal disease in HIV-infected individuals: a tale of two races. Journal of Infectious Diseases 197 (online edition), 2008.

Wyatt CM. HIV and the kidney: a spotlight on racial differences. Journal of Infectious Diseases 197 (online edition), 2008.