New Study Questions Accuracy of Kidney Function Tests Used Across NHS

Research presented at UK Kidney Week reveals widely used diagnostic equations may misclassify kidney disease, especially affecting ethnic minority patients.

Dr Sarah Chen watched the numbers flash across her screen at Maidstone Hospital’s nephrology unit. The kidney function test showed her patient’s estimated glomerular filtration rate – an important measurement that determines whether someone has chronic kidney disease and what treatment they need.

But groundbreaking research presented at UK Kidney Week this month suggests those numbers might not tell the whole story.

Study Findings

The AIM CKD UK study, spanning 13 years and involving 15,879 adults across 11 UK centres, has revealed that all five commonly used equations for estimating kidney function systematically overestimate how well kidneys are working. The research, conducted between 2009 and 2022, compared these mathematical formulas against actual measured kidney function – the gold standard that requires complex hospital procedures.

The findings paint a troubling picture of diagnostic accuracy. The widely used CKD-EPI-2021 equation achieved only 70.1% accuracy overall, dropping to a concerning 58% in South Asian participants. Even more alarming, this equation overestimates kidney function by 18 mL/min/1.73m² in South Asian patients – a difference that could delay critical treatment.

A Tale of Two Equations

Not all equations performed equally poorly. The Lund-Malmö Revised equation emerged as the clear winner, achieving 86% accuracy overall and 87% in White participants, with the lowest bias at just 1.4 mL/min/1.73m².

The clinical implications stretch far beyond academic interest. When researchers examined how equation choice affected disease staging, they found CKD-EPI equations correctly staged chronic kidney disease in only 55-60% of cases, compared to 65% using the more accurate Lund-Malmö method.

Potential Treatment Implications

These aren’t just statistical quirks – they translate into real-world consequences for patients. The research suggests treatment eligibility differences could delay therapy such as Dapagliflozin in up to half of patients, depending on which equation clinicians use.

The study addresses gaps identified by National Institute for Health and Care Excellence guidance reliability of creatinine-based equations, especially in younger adults and minority populations where accuracy concerns have long simmered beneath the surface.

Lead researcher Gama R and colleagues presented their findings at UK Kidney Week, held from 10-12 March 2026, calling for urgent review of current diagnostic practices.

Key Takeaways

All five commonly used kidney function equations systematically overestimate actual kidney performance

The Lund-Malmö Revised equation shows markedly better accuracy (86%) compared to current NHS standard CKD-EPI-2021 (70.1%)

South Asian patients face particular diagnostic challenges, with accuracy dropping to just 58% using current methods

What This Means for Kent Residents

Kent residents from ethnic minority backgrounds, especially those of South Asian heritage, may have experienced delayed kidney disease diagnosis or treatment due to these equation inaccuracies. NHS Kent and Medway ICB services will likely need to review their diagnostic protocols to ensure equitable care across all communities. Patients concerned about previous kidney function tests should discuss these findings with their GP, who can arrange reassessment if clinically appropriate – though anyone experiencing symptoms like persistent fatigue, swelling, or changes in urination should contact NHS 111 for immediate guidance.

Published: 24 March 2026

Source: @bmj_latest on X. This article has been researched and rewritten with editorial balance by Kent Local News.