Factors associated with iohexol-based glomerular filtration rate slope over 36 months in HIV-negative and HIV-positive individuals

Background: Monitoring kidney function is important in HIV-positive persons, but creatinine-based estimates of glomerular filtration rate (GFR) have limitations. There are little to no data available assessing GFR trends in HIV-positive persons using a gold-standard measure of GFR. Methods: We measured GFR based on iohexol plasma disappearance (iGFR) annually for 3 years in nondiabetic, HIV-negative and HIV-positive volunteers with normal estimated kidney function. We used mixed linear models to evaluate factors associated with baseline iGFR and iGFR slope. Results: One hundred HIV-negative and 191 HIV-positive, predominantly black individuals (median age 49 years) participated in the study and completed a total of 960 iGFR assessments over a median of 36 months. Despite similar estimated GFR at baseline, average iGFR values were lower in HIV-positive compared with HIV-negative participants (103.2 vs. 110.8, ml/min/1.73 m 2, P=0.004). However, subsequent iGFR slope was not significantly different in HIV-positive and HIV-negative participants. In the HIV-positive group, the presence of carotid plaque and hepatitis C virus coinfection were associated with significantly lower iGFR values at baseline. A nonsuppressed HIV RNA level at baseline was associated with a significantly more rapid iGFR decline compared with individuals with HIV RNA less than 400copies/ml (-4.69 vs.-1.31ml/min per 1.73m 2 per year, P=0.005). Other factors significantly associated with iGFR slope included albuminuria and glycosylated hemoglobin. Conclusion: Compared with HIV-negative persons, HIV-positive participants had significantly lower baseline iGFR, despite similar estimated GFR in the two groups. Nonsuppressed HIV RNA at baseline was associated with a more rapid iGFR decline over 3 years.