A national analysis of more than 47 million laboratory results has found that reduced estimated glomerular filtration rate (eGFR) was common among adults undergoing creatinine testing in South Africa’s public health sector between 2018 and 2024.
From 83,390,060 raw records, 80,289,377 remained after cleaning. An eGFR below 60 mL/min/1.73 m² occurred in 6,066,893 person-quarters, or 12.69 percent, while an eGFR below 30 mL/min/1.73 m² occurred in 1,299,488 person-quarters, or 2.72 percent.
The choice of result selection mattered. When the lowest quarterly value was selected instead of the first valid result, the proportions rose to 13.22 percent below 60 and 3.03 percent below 30, a sensitivity analysis that illustrates how sampling of laboratory values can shift measured proportions.
Geographic variation was evident after standardisation for age, sex and year. The standardised proportions of person-quarters with eGFR below 30 were highest in Limpopo at 3.45 percent, followed by the Northern Cape at 3.00 percent and the Free State at 2.94 percent, and lowest in the Western Cape at 2.18 percent. These are standardised estimates describing tested adults, not community prevalence figures.
Agreement was 95.68 percent at the threshold of 60, with a kappa of 0.8292, and 99.81 percent at the threshold of 30, with a kappa of 0.9645, indicating substantial to near-perfect agreement between the two equations in this laboratory setting.
Temporal patterns differed by threshold. Standardised quarterly proportions below 30 ranged narrowly from 2.37 percent to 3.07 percent over the study window, while standardised quarterly proportions below 60 increased overall, though with fluctuation across the period.
A technical caveat concerns the equation implementation. Numerical matching suggested the laboratory used the 2009 CKD-EPI equation without its Black-race multiplier, but laboratory-specific implementation metadata were unavailable, leaving some uncertainty about exactly how eGFR values were computed across facilities.
The authors are careful about interpretation. The results describe laboratory-reported eGFR phenotypes among people who underwent creatinine testing in the public sector, not community chronic kidney disease prevalence, and the findings were not validated against measured GFR. Changes in testing patterns and clinical case mix over time may affect the observed trends.
The study’s scale demonstrates the potential of routinely collected laboratory data to serve as a surveillance tool in a country that lacks routine national monitoring of kidney function. The authors note that future surveillance would require linkage to clinical data, complementary biomarkers such as albuminuria, and measurement metadata to strengthen interpretation of laboratory-reported kidney function phenotypes.
Subject of Research: Laboratory-reported kidney function phenotypes among adults undergoing public-sector creatinine testing in South Africa from 2018 to 2024
Article Title: Kidney function phenotypes among adults undergoing public-sector creatinine testing in South Africa, 2018–2024: a national retrospective repeated cross-sectional study of routinely collected laboratory data
Article References: Pillay, S., & Mahabeer, P. (2026). Kidney function phenotypes among adults undergoing public-sector creatinine testing in South Africa, 2018–2024: a national retrospective repeated cross-sectional study of routinely collected laboratory data. BMC Nephrology. https://doi.org/10.1186/s12882-026-05462-3
Image Credits: AI Generated
DOI: 10.1186/s12882-026-05462-3
Keywords: chronic kidney disease, eGFR, creatinine, South Africa, National Health Laboratory Service, CKD-EPI, MDRD, cross-sectional study, kidney function surveillance, public health laboratory data, Kidney, function
News Source: Jerry Hayes. (October 29, 2026). Reduced Kidney Function Found in Nearly One in Eight Tested South African Adults. Scienmag.
