Kidney function of HIV-infected children in Lagos, Nigeria: using Filler's serum cystatin C-based formula

Background: Limited data is available on kidney function in HIV-infected children in sub-Saharan Africa. In addition, malnutrition in these children further reduces the utility of diagnostic methods such as creatinine-based estimates of glomerular filtration rate. We determined the serum cystatin C level and estimated glomerular filtration rate of 60 antiretroviral-na ve, HIV-infected children and 60 apparently healthy age and sex matched children. Methods: Serum cystatin C level was measured using enzyme-linked immunosorbent assay technique, while glomerular filtration rate was estimated using Filler's serum cystatin C formula. Student t test, Mann Whitney U test, Pearson chi square and Fisher's exact test were used, where appropriate, to test difference between groups. Results: Compared to the controls, the HIV-infected group had significantly higher median (interquartile range) serum cystatin C levels {0.77 (0.29) mg/l versus 0.66 (0.20) mg/l; p = 0.025} and a higher proportion of children with serum cystatin C level > 1 mg/l {10 (16.7%) versus one (1.7%); p = 0.004}. The HIV-infected children had a mean (+/- SD) eGFR of 96.8 (+/- 36.1) ml/min/1.73 m(2) compared with 110.5 (+/- 27.8) ml/min/1.73 m2 in the controls (p = 0.021). After controlling for age, sex and body mass index, only the study group (HIV infected versus control) remained a significant predictor of serum cystatin C level (beta = -0.216, p = 0.021). The proportion of HIV-infected children with eGFR < 60 ml/min/1.73 m(2) was eight (13.3%) versus none (0%) in the control group (p = 0.006). However, the serum cystatin C level, eGFR and proportions of children with serum cystatin C level > 1 mg/l and eGFR < 60 ml/min/1.73 m(2) were not significantly different between the HIV-infected children with advanced disease and those with milder disease. Conclusions: HIV-infected children in Nigeria have higher serum cystatin C level and lower eGFR compared to age and sex matched controls.