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

Abstract

BackgroundLimited 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-naïve, HIV-infected children and 60 apparently healthy age and sex matched children.MethodsSerum 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.ResultsCompared 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 m2 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 (β = -0.216, p = 0.021). The proportion of HIV-infected children with eGFR <60 ml/min/1.73 m2 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 m2 were not significantly different between the HIV-infected children with advanced disease and those with milder disease.ConclusionsHIV-infected children in Nigeria have higher serum cystatin C level and lower eGFR compared to age and sex matched controls.

The use of estimated glomerular filtration rate in the evaluation of renal function in HIV-positive children in Enugu

“…[3,11] It is easy to use, but best predicts stages 3-5 CKD and, therefore, may not detect an early decline in renal function. [6] Esezobor and co-workers [15] documented eGFR of less than 60 mls/min/1.73 m 2 in 13.3% of their subject, using Cystatin C-based formula.…”

Cystatin C

“…16,17 In both cases, consistently higher cystatin C levels and lower cystatin-calculated GFR were reported in HIV-infected children compared with healthy controls. The authors attribute these findings to a high rate of HIV-associated nephropathy and chronic kidney disease in their cohorts, but HIV viral load or markers of inflammation were not performed; therefore, the influence of the inflammatory status on cystatin C levels (and cystatin-calculated GFR) could not be taken into account in these studies.…”

“…Mean cystatin C levels (0.87 mg/L) in our study are lower than those reported by other studies in pediatric (1.01 mg/L) 16 and adult HIV cohorts (1.03 mg/L) 38 ; most importantly, no differences in cystatin C values were found with healthy controls, as opposed to previous studies. 16,17,39,40 The optimal immunologic and clinical situation in our cohort, including renal function, probably explains these findings. Only 2 of 83 patients showed estimated GFR <90 and none <60 mL/min/1.73m 2 in our study; of note, both girls were receiving HAART regimens including tenofovir.…”

“…Consistent with these properties, in our results, age, gender and BMI did not affect cystatin C levels as described previously. 16,17,26,27 When a renal injury occurs, cystatin C plasma levels increase. [23][24][25]27 Other conditions that may influence cystatin C values are thyroid illness, corticosteroid therapy and chronic viral infections, such as HIV infection.…”

“…14,15 Data on cystatin C in HIV-infected children are very limited. 16,17 In this study, we determined cystatin C plasma levels in a large cohort of HIV-infected children and adolescents, and how these levels correlated with markers of renal function and inflammation.…”