THE KIDNEY FAILURE RISK EQUATION: WHO SHOULD WE REFER?

NICE added the kidney failure risk equation (KFRE) to CKD guidance in 2021. It helps find patients most at risk of needing renal replacement therapy. To find the five-year risk score, just use age, sex, eGFR, and urine albumin-creatinine ratio. Then, refer anyone with a score above 5% to nephrology.¹

A new study published in the BJGP this week suggests the picture is more complicated than that.²

Stewart and his team looked at CKD stages 3 to 5 patients. They used the Greater Manchester Care Record from 2018 to 2023. This is a large primary care dataset covering a diverse urban population. They calculated KFRE scores. They tracked the outcomes. Did patients start dialysis, receive a transplant, or die first?

The findings are striking. For patients with a KFRE score below 5% (the group NICE says does not need referral), the probability of needing renal replacement therapy was just 0.1%. The probability of death was 11.9%. For those scoring 5 to 20%, the probability of renal replacement therapy was 2%, but the probability of death rose to 23%. Even in the highest risk group, with KFRE scores above 20%, death (29%) was more likely than renal replacement therapy (14%).

In other words, for most patients flagged by the KFRE, the competing risk of dying from something else outweighs the risk of ever reaching dialysis. That does not mean the referral is wrong. Nephrology input can support conservative management, medication optimisation, and advance care planning. But it does change the nature of the conversation.

The most important finding was the equity dimension. Black and Asian patients with KFRE scores over 20% were more likely to need renal replacement therapy than to die. This is the opposite pattern to the overall cohort. Current NICE guidance doesn’t address ethnicity in referral decisions. It also doesn’t mention the risk of death. The authors argue it should.

Around 11% of patients with CKD stages 3 to 5 in this cohort had a KFRE score above 5%, which gives a rough sense of the workload implications. It also raises a practical question: if someone does not measure a uACR, they cannot calculate the KFRE. Including uACR in every CKD review is a prerequisite for making this tool useful at all.

What could this mean for primary care?

The KFRE is a useful tool, but it tells you about kidney failure risk in isolation. It doesn't consider that many CKD patients, especially elderly with other health issues, are much more likely to die than to need dialysis. For these patients, a nephrology referral might focus on conservative management and advance care planning instead of preparing for renal replacement. For younger patients and those from Black and Asian backgrounds, the KFRE score is more important. This is because they have a lower risk of dying from other causes, but a higher chance of reaching kidney failure.

References

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