Clinical Research: Validation of eGFR formulae and Point-of-Care Creatinine measurements in the Assessment of kidney function in Africans

Name: June Fabian

Hospital / Affiliation: Wits Donald Gordon Medical Centre/ University of the Witwatersrand

Home Country: South Africa

Host Country: n/a

Year: 2016

Status of your program: IN PROGRESS

Title of the project: 

Validation of eGFR formulae and Point-of-Care Creatinine measurements in the Assessment of kidney function in Africans

Topic: 

Chonic Kidney Disease

Short description of the project or abstract: 

This project aims to investigate currently available methods to assess kidney function in Africans. Early detection of chronic kidney disease (CKD) is based on simple routine laboratory tests such as urine protein and serum creatinine. A recent meta-analysis of data from several African countries showed the overall prevalence of CKD was 13.9%[1]. They noted an absence of validated and reliable measures of kidney function for Africans in Africa and noted that the prevalence estimates varied substantially even within similar populations depending on the definition of CKD used and the method of measurement.
Serum creatinine levels have been shown to be higher in African Americans regardless of kidney function. In response to this, adjustments for ethnicity have been included in the 4-variable MDRD and the CKD-EPI equations. Data from our centre has shown that these equations perform better without the adjustment for ethnicity. This has also been demonstrated in studies from Kwa-Zulu Natal and Western Cape, South Africa. Studies from Kenya and Ghana also showed an over-estimation of the GFR with the adjustment for ethnicity. In all of these sub-Saharan African studies, the BMI and weight of all participants was lower than in studies from Europe and the USA, suggesting that lower muscle mass may contribute to this phenomenon. However, the single limiting factor, for all these studies has been in the small sample size.

To date, there have been no population-based studies that have validated the use of eGFR equations in South Africans. In this study we will determine how best to measure kidney function accurately using serum creatinine and cystatin C (cysC). We will do this by comparing the accuracy of different equations for calculating glomerular filtration rate (eGFR) to a directly measured GFR using iohexol (iGFR). We will use an appropriately large sample size that will allow the derivation of a new equation that accurately predicts kidney function in black Africans. This will be determinant to future diagnosis and management of patients with CKD in South Africa as well as for the conduct of future epidemiological studies. We will also assess the accuracy and precision of a point of care device for determination of estimated GFR. This is essential to determine whether existing devices are sufficiently accurate for assessing kidney function in resource-limited areas.

Learning or Research objectives:

• To evaluate the accuracy and precision of the MDRD and the CKD-EPI with and without the inclusion of the ethnicity factor to iGFR
• To compare the accuracy and the precision of the CKD-EPI cysC and combined cysC, creatinine equation to iGFR
• To develop a new equation for use in black Africans that may include the use of other variables such as height
• To assess the accuracy of a point of care device(POC) for the estimation of GFR