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Comparison of Various Equations for Estimating GFR in Malawi: How to Determine Renal Function in Resource Limited Settings?

Glaser N, Deckert A, Phiri S, Rothenbacher D, Neuhann F - PLoS ONE (2015)

Bottom Line: Comparison of formulae based on Bland-Altman-plots and accuracy revealed best performance for the CKD-EPI equation without the correction factor for black Americans.Analyzing the differences between HIV-positive and -negative individuals CKD-EPI systematically overestimated eGFR in comparison to cystatin C and therefore lead to underestimation of CKD in HIV-positives.Our findings underline the importance for standardization of eGFR calculation in a Sub-Saharan African setting, to further investigate the differences with regard to HIV status and to develop potential correction factors as established for age and sex.

View Article: PubMed Central - PubMed

Affiliation: Institute of Public Health, University of Heidelberg, Heidelberg, Germany.

ABSTRACT

Background: Chronic kidney disease (CKD) is a probably underrated public health problem in Sub-Saharan-Africa, in particular in combination with HIV-infection. Knowledge about the CKD prevalence is scarce and in the available literature different methods to classify CKD are used impeding comparison and general prevalence estimates.

Methods: This study assessed different serum-creatinine based equations for glomerular filtration rates (eGFR) and compared them to a cystatin C based equation. The study was conducted in Lilongwe, Malawi enrolling a population of 363 adults of which 32% were HIV-positive.

Results: Comparison of formulae based on Bland-Altman-plots and accuracy revealed best performance for the CKD-EPI equation without the correction factor for black Americans. Analyzing the differences between HIV-positive and -negative individuals CKD-EPI systematically overestimated eGFR in comparison to cystatin C and therefore lead to underestimation of CKD in HIV-positives.

Conclusions: Our findings underline the importance for standardization of eGFR calculation in a Sub-Saharan African setting, to further investigate the differences with regard to HIV status and to develop potential correction factors as established for age and sex.

No MeSH data available.


Related in: MedlinePlus

Cystatin C (van Deventer) vs. Cockcroft-Gault.The coloured lines represent the mean differences of the two equations to be compared at every point of the mean of the estimated GFRs, by HIV status; the coloured shaded areas mark the limits of agreement, which are mean- differences plus or minus two standard-deviations. Assuming a normal distribution, 95% of the dots are expected to appear within the limits of agreement. [40] Closer margins reflect a higher agreement of the different methods.
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pone.0130453.g001: Cystatin C (van Deventer) vs. Cockcroft-Gault.The coloured lines represent the mean differences of the two equations to be compared at every point of the mean of the estimated GFRs, by HIV status; the coloured shaded areas mark the limits of agreement, which are mean- differences plus or minus two standard-deviations. Assuming a normal distribution, 95% of the dots are expected to appear within the limits of agreement. [40] Closer margins reflect a higher agreement of the different methods.

Mentions: Figs 1–3 present the comparisons of the different creatinine equations with the cystatin C equation (van Deventer) without the correction factor for black Americans. All comparisons show an increasing agreement with increasing mean eGFR for HIV negatives (narrowing limits of agreement). All comparisons show differences with respect to HIV status; hence, the creatinine based eGFR of HIV positives seems to be higher in general. For cystatin C vs. CKD-EPI, the mean differences regression line remains closest to zero over the entire range for HIV-negatives, indicating almost no trend in the bias, while for cystatin C vs. MDRD-4 and cystatin C vs. Cockcroft-Gault, the course of the regression line has a strong tendency. The Cockcroft-Gault formula shows the smallest mean differences between HIV-positives and-negatives, most likely because it controls for body weight. Altogether, cystatin C vs. CKD-EPI is least biased for both HIV negatives and positives and has the tightest limits of agreement. A sensitivity analysis using the cystatin C based equation evaluated by CKD-EPI showed similar results as the Cystatin C formula by Deventer et al., CKD-EPI creatinine still performed best compared to Cockcroft-Gault and MDRD-4 (see supplementary figures in S1, S2, S3, S4, S5, and S6 Figs). However, the variation was increased in general.


Comparison of Various Equations for Estimating GFR in Malawi: How to Determine Renal Function in Resource Limited Settings?

Glaser N, Deckert A, Phiri S, Rothenbacher D, Neuhann F - PLoS ONE (2015)

Cystatin C (van Deventer) vs. Cockcroft-Gault.The coloured lines represent the mean differences of the two equations to be compared at every point of the mean of the estimated GFRs, by HIV status; the coloured shaded areas mark the limits of agreement, which are mean- differences plus or minus two standard-deviations. Assuming a normal distribution, 95% of the dots are expected to appear within the limits of agreement. [40] Closer margins reflect a higher agreement of the different methods.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4470826&req=5

pone.0130453.g001: Cystatin C (van Deventer) vs. Cockcroft-Gault.The coloured lines represent the mean differences of the two equations to be compared at every point of the mean of the estimated GFRs, by HIV status; the coloured shaded areas mark the limits of agreement, which are mean- differences plus or minus two standard-deviations. Assuming a normal distribution, 95% of the dots are expected to appear within the limits of agreement. [40] Closer margins reflect a higher agreement of the different methods.
Mentions: Figs 1–3 present the comparisons of the different creatinine equations with the cystatin C equation (van Deventer) without the correction factor for black Americans. All comparisons show an increasing agreement with increasing mean eGFR for HIV negatives (narrowing limits of agreement). All comparisons show differences with respect to HIV status; hence, the creatinine based eGFR of HIV positives seems to be higher in general. For cystatin C vs. CKD-EPI, the mean differences regression line remains closest to zero over the entire range for HIV-negatives, indicating almost no trend in the bias, while for cystatin C vs. MDRD-4 and cystatin C vs. Cockcroft-Gault, the course of the regression line has a strong tendency. The Cockcroft-Gault formula shows the smallest mean differences between HIV-positives and-negatives, most likely because it controls for body weight. Altogether, cystatin C vs. CKD-EPI is least biased for both HIV negatives and positives and has the tightest limits of agreement. A sensitivity analysis using the cystatin C based equation evaluated by CKD-EPI showed similar results as the Cystatin C formula by Deventer et al., CKD-EPI creatinine still performed best compared to Cockcroft-Gault and MDRD-4 (see supplementary figures in S1, S2, S3, S4, S5, and S6 Figs). However, the variation was increased in general.

Bottom Line: Comparison of formulae based on Bland-Altman-plots and accuracy revealed best performance for the CKD-EPI equation without the correction factor for black Americans.Analyzing the differences between HIV-positive and -negative individuals CKD-EPI systematically overestimated eGFR in comparison to cystatin C and therefore lead to underestimation of CKD in HIV-positives.Our findings underline the importance for standardization of eGFR calculation in a Sub-Saharan African setting, to further investigate the differences with regard to HIV status and to develop potential correction factors as established for age and sex.

View Article: PubMed Central - PubMed

Affiliation: Institute of Public Health, University of Heidelberg, Heidelberg, Germany.

ABSTRACT

Background: Chronic kidney disease (CKD) is a probably underrated public health problem in Sub-Saharan-Africa, in particular in combination with HIV-infection. Knowledge about the CKD prevalence is scarce and in the available literature different methods to classify CKD are used impeding comparison and general prevalence estimates.

Methods: This study assessed different serum-creatinine based equations for glomerular filtration rates (eGFR) and compared them to a cystatin C based equation. The study was conducted in Lilongwe, Malawi enrolling a population of 363 adults of which 32% were HIV-positive.

Results: Comparison of formulae based on Bland-Altman-plots and accuracy revealed best performance for the CKD-EPI equation without the correction factor for black Americans. Analyzing the differences between HIV-positive and -negative individuals CKD-EPI systematically overestimated eGFR in comparison to cystatin C and therefore lead to underestimation of CKD in HIV-positives.

Conclusions: Our findings underline the importance for standardization of eGFR calculation in a Sub-Saharan African setting, to further investigate the differences with regard to HIV status and to develop potential correction factors as established for age and sex.

No MeSH data available.


Related in: MedlinePlus