Predictive performance of eGFR equations in South Africans of African and Indian ancestry compared with 99mTc-DTPA imaging

Madala, Nomandla; Nkwanyana, None Ntombifikile M.; Dubula, Thozama; Naiker, Indiran P.

doi:10.1007/s11255-011-9928-7

Cited by 36 publications

(32 citation statements)

References 23 publications

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“…We calculated eGFR using the following equations: MDRD: eGFR (mL/min/1.73 m 2 ) = 175 × (serum creatinine (Scr) (µmol/L)/88.4) −1.154 × (Age) −0.203 (× 0.742 if female) [31]; CKD-EPI: eGFR (mL/min/1.73 m 2 ) = 144 × (0.993) age × ((Scr (µmol/L)/88.4)/0.7) −0.329 (if female and Scr ≤62 µmol/L) or ((Scr (µmol/L)/88.4)/0.7) −1.209 (if female and Scr >62 µmol/L) or ((Scr (µmol/L)/88.4)/0.9) −0.411 (if male and Scr ≤80 µmol/L) or ((Scr (µmol/L)/88.4)/0.9) −1.209 (if male and Scr >80 µmol/L) [32]; and Cockcroft-Gault: eGFR (mL/min) = ((140-age) × weight × 1.228)/Scr (μmol/L) (× 0.85 if female) [33]. Although the MDRD and CKD-EPI equations include a factor for Black race, we did not adjust eGFR for race in this study for the following reasons: (i) the equations were derived in African American patients not Southern African patients [31,32] and South African studies have found that eGFR calculated without the race factor is more accurate when compared to measured GFR for both the MDRD [34,35] and CKD-EPI equations [23,24]; (ii) the study sites do not routinely collect race data. Weights were not always recorded on the same dates as creatinine concentrations, so we matched weights to creatinine concentrations to calculate Cockcroft-Gault eGFR.…”

Section: Methodsmentioning

confidence: 99%

Changes in estimated glomerular filtration rate over time in South African HIV‐1‐infected patients receiving tenofovir: a retrospective cohort study

Waal

Cohen

Fox

et al. 2017

Journal of the International AIDS Society

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Introduction: Tenofovir has been associated with decline in kidney function, but in patients with low baseline kidney function, improvements over time have been reported. Additionally, the magnitude and trajectory of estimated glomerular filtration rate (eGFR) changes may differ according to how eGFR is calculated. We described changes in eGFR over time, and the incidence of, and risk factors for, kidney toxicity, in a South African cohort.Methods: We included antiretroviral-naïve patients ≥16 years old who started tenofovir-containing antiretroviral therapy (ART) between 2002 and 2013. We calculated eGFR using the Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), and Cockcroft-Gault equations. We described changes in eGFR from ART initiation using linear mixed effects regression. We described the incidence of eGFR <30 mL/min on treatment, and identified associations with low eGFR using Cox regression.Results: We included 15156 patients with median age of 35.4 years (IQR 29.9–42.0), median CD4 cell count of 168 cells/µL (IQR 83–243), and median eGFR (MDRD) of 98.6 mL/min (IQR 84.4–115.6). Median duration of follow up on tenofovir was 12.9 months (IQR 5.1–23.3).Amongst those with a baseline and subsequent eGFR available, mean eGFR change from baseline at 12 months was −4.4 mL/min (95% CI −4.9 to −4.0), −2.3 (−2.5 to −2.1), and 0.6 (0.04 to 1.2) in those with baseline eGFR ≥90 mL/min; and 11.9 mL/min (11.0 to 12.7), 14.6 (13.5 to 15.7), and 11.0 (10.3 to 11.7) in those with baseline eGFR <90 mL/min, according to the MDRD, CKD-EPI (n = 11 112), and Cockcroft-Gault (n = 9 283) equations, respectively.Overall, 292 (1.9%) patients developed eGFR <30 mL/min. Significant associations with low eGFR included older age, baseline eGFR <60 mL/min, CD4 count <200 cells/µL, body weight <60 kg, and concomitant protease inhibitor use.Conclusions: Patients on tenofovir with baseline eGFR ≥90 mL/min experienced small but significant declines in eGFR over time when eGFR was estimated using the MDRD or CKD-EPI equations. However, eGFR increased in patients with eGFR <90 mL/min, regardless of which estimating equation was used. Decreases to below 30 mL/min were uncommon. In settings with limited access to laboratory testing, monitoring guidelines should consider focusing on higher risk patients.

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Section: Methodsmentioning

confidence: 99%

Changes in estimated glomerular filtration rate over time in South African HIV‐1‐infected patients receiving tenofovir: a retrospective cohort study

Waal

Cohen

Fox

et al. 2017

Journal of the International AIDS Society

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“…Van Deventer et al [22] reported better performance of the MDRD equation in South Africans of African origin when the correction factor for black ethnicity was not used. Madala et al [23] also concluded that the MDRD equation should be used without the correction factor, and suggested that a new correction factor, or a new equation, is needed for South Africans of Indian origin.…”

Section: Discussionmentioning

confidence: 99%

“…Most of the participants in this study will be of mixed ethnicity. It would also be very useful to have the data from the studies by Van Deventer et al [22] and Madala et al [23] re-analysed to include the CKD-EPI equation. A second issue is related to our recruitment methods.…”

Section: Discussionmentioning

confidence: 99%

Prevalence of chronic kidney disease and association with cardiovascular risk factors among teachers in Cape Town, South Africa

et al. 2017

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Background: There is a need to determine the feasibility of conducting studies of chronic diseases among large cohorts of African patients. One aim of the South African feasibility study was to determine the prevalence of chronic kidney disease (CKD) and its association with cardiovascular disease (CVD) risk factors among school teachers. Methods: In a cross-sectional survey of 489 teachers we captured data on demographics, CVD risk factors, anthropometry and blood pressure. Serum glucose, creatinine, cholesterol and urine protein/creatinine ratio was measured. Glomerular filtration rate was estimated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and the Modification of Diet in Renal Disease study equations. Results: The mean (± standard deviation) age of the participants was 46.3 ± 8.5 years, with 70.3% being female and 74.6% of mixed ethnicity. The crude prevalence of CKD using the CKD-EPI equation was 6.1% while the age-adjusted prevalence was 6.4% (95% confidence interval 3.2–9.7%). CKD was associated with the presence of diabetes and higher diastolic blood pressures. Conclusions: In our study population of relatively young, working individuals CKD was common, clinically silent and associated with cardiovascular risk factors. The long-term complications of CKD are serious and expensive to manage and this, therefore, constitutes an important public health problem for South Africa.

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“…Whilst GFR-estimating equations have been validated in African-Caribbean communities from North America [29] and endemic Asian populations [30-35] there is no independent validation in British African-Caribbean populations; and no data at all amongst people originating from India, Pakistan, Sri Lanka and Bangladesh). There is some evidence that the black ethnicity coefficients in GFR estimating equations developed for use amongst African-Americans may not be transferable to other populations of African ancestry [36,37]. …”

Section: Introductionmentioning

confidence: 99%

The eGFR-C study: accuracy of glomerular filtration rate (GFR) estimation using creatinine and cystatin C and albuminuria for monitoring disease progression in patients with stage 3 chronic kidney disease - prospective longitudinal study in a multiethnic population

et al. 2014

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BackgroundUncertainty exists regarding the optimal method to estimate glomerular filtration rate (GFR) for disease detection and monitoring. Widely used GFR estimates have not been validated in British ethnic minority populations.Methods/designIohexol measured GFR will be the reference against which each estimating equation will be compared. The estimating equations will be based upon serum creatinine and/or cystatin C. The eGFR-C study has 5 components:1) A prospective longitudinal cohort study of 1300 adults with stage 3 chronic kidney disease followed for 3 years with reference (measured) GFR and test (estimated GFR [eGFR] and urinary albumin-to-creatinine ratio) measurements at baseline and 3 years. Test measurements will also be undertaken every 6 months. The study population will include a representative sample of South-Asians and African-Caribbeans. People with diabetes and proteinuria (ACR ≥30 mg/mmol) will comprise 20-30% of the study cohort.2) A sub-study of patterns of disease progression of 375 people (125 each of Caucasian, Asian and African-Caribbean origin; in each case containing subjects at high and low risk of renal progression). Additional reference GFR measurements will be undertaken after 1 and 2 years to enable a model of disease progression and error to be built.3) A biological variability study to establish reference change values for reference and test measures.4) A modelling study of the performance of monitoring strategies on detecting progression, utilising estimates of accuracy, patterns of disease progression and estimates of measurement error from studies 1), 2) and 3).5) A comprehensive cost database for each diagnostic approach will be developed to enable cost-effectiveness modelling of the optimal strategy.The performance of the estimating equations will be evaluated by assessing bias, precision and accuracy. Data will be modelled as a linear function of time utilising all available (maximum 7) time points compared with the difference between baseline and final reference values. The percentage of participants demonstrating large error with the respective estimating equations will be compared. Predictive value of GFR estimates and albumin-to-creatinine ratio will be compared amongst subjects that do or do not show progressive kidney function decline.DiscussionThe eGFR-C study will provide evidence to inform the optimal GFR estimate to be used in clinical practice.Trial registrationISRCTN42955626.

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Predictive performance of eGFR equations in South Africans of African and Indian ancestry compared with 99mTc-DTPA imaging

Abstract: MDRD-eGFR calculated without the African-American correction factor improved GFR prediction in African CKD patients and using the MDRD correction factor of 1.0 in Indian patients as in Caucasians may be inappropriate.

Cited by 36 publications

References 23 publications

Changes in estimated glomerular filtration rate over time in South African HIV‐1‐infected patients receiving tenofovir: a retrospective cohort study

Changes in estimated glomerular filtration rate over time in South African HIV‐1‐infected patients receiving tenofovir: a retrospective cohort study

Prevalence of chronic kidney disease and association with cardiovascular risk factors among teachers in Cape Town, South Africa

The eGFR-C study: accuracy of glomerular filtration rate (GFR) estimation using creatinine and cystatin C and albuminuria for monitoring disease progression in patients with stage 3 chronic kidney disease - prospective longitudinal study in a multiethnic population

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