Chronic Kidney Disease and Estimates of Kidney Function in HIV Infection: A Cross-Sectional Study in the Multicenter AIDS Cohort Study

Background: Cystatin C has been proposed as an alternative marker of kidney function among HIV-infected persons in whom serum creatinine is affected by extrarenal factors. Methods: In this cross-sectional study, we compared estimated glomerular filtration rates (eGFR) using serum creatinine versus cystatin C between 150 HIV-uninfected and 783 HIV-infected men. We evaluated the prevalence of chronic kidney disease (CKD; eGFR less than 60 mL/min/1.73 m(2)) and examined the influence of extrarenal factors on GFR estimates among HIV-infected men. Results: Estimated GFR(SCR) was similar by HIV serostatus, but eGFR(CYSC) was lower in HIV-infected men. A higher proportion of HIV-infected men were classified as having CKD when using eGFR(CYSC) versus eGFR(SCR) (7% vs 5%, P < 0.01). In HIV-infected individuals without CKD, eGFR(SCR) was higher than eGFR(CYSC), whereas it was lower than eGFR(CYSC) in persons with CKD. In HIV-infected men, older age, proteinuria, and prior clinical AIDS were inversely associated with both GFR estimates. Higher serum albumin levels and angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use were associated with lower eGFR(SCR). HIV viral load, hepatitis C coinfection, and serum alkaline phosphatase were inversely associated with eGFR(CYSC). Conclusion: Among HIV-uninfected and HIV-infected men of similar social risk behaviors, GFR estimates differed by biomarker and kidney function level. Estimated GFR(CYSC) classified a larger proportion of HIV-infected men with CKD compared with eGFR(SCR). Differences between these GFR-estimating methods may be the result of the effects of extrarenal factors on serum creatinine and cystatin C. Until GFR-estimating equations are validated among HIV-infected individuals, current GFR estimates based on these biomarkers should be interpreted with care in this patient population.