Cystatin C level as a marker of kidney function in human immunodeficiency virus infection - The FRAM study

Background: Although studies have reported a high prevalence of end-stage renal disease in human immunodeficiency virus (HIV)-infected individuals, little is known about moderate impairments in kidney function. Cystatin C measurement may be more sensitive than creatinine for detecting impaired kidney function in persons with HIV. Methods: We evaluated kidney function in the Fat Redistribution and Metabolic Change in HIV Infection (FRAM) cohort, a representative sample of 1008 HIV-infected persons and 290 controls from the Coronary Artery Risk Development in Young Adults (CARDIA) study in the United States. Results: Cystatin C level was elevated in HIV-infected individuals; the mean +/- SD cystatin C level was 0.92 +/- 0.22 mg/L in those infected with HIV and 0.76 +/- 0.15 mg/L in controls (P < .001). In contrast, both mean creatinine levels and estimated glomerular filtration rates appeared similar in HIV-infected individuals and controls (0.87 +/- 0.21 vs 0.85 +/- 0.19 mg/dL [to convert to micromoles per liter, multiply by 88.4] [P=.35] and 110 +/- 26 vs 106 +/- 23 mL/min/ 1.73 m(2) [P=.06], respectively). Persons with HIV infection were more likely to have a cystatin C level greater than 1.0 mg/L (OR, 9.8; 95% confidence interval, 4.4-22.0 [P < .001]), a threshold demonstrated to be associated with increased risk for death and cardiovascular and kidney disease. Among participants with HIV, potentially modifiable risk factors for kidney disease, hypertension, and low high-density lipoprotein concentration were associated with a higher cystatin C level, as were lower CD4 lymphocyte count and coinfection with hepatitis C virus (all P < .001). Conclusions: Individuals infected with HIV had substantially worse kidney function when measured by cystatin C level compared with HIV-negative controls, whereas mean creatinine levels and estimated glomerular filtration rates were similar. Cystatin C measurement could be a useful clinical tool to identify HIV-infected persons at increased risk for kidney and cardiovascular disease.