IgA risk score: A Commentary

A New International Risk Prediction Tool in IgA Nephropathy

How can you give advice about prognosis to an individual recently diagnosed with IgA nephropathy (IgAN)?

This is a clinical problem regularly faced by nephrologists. We believe that the International IgAN Risk Prediction Tool, developed by the International IgA Nephropathy Network, and just published in JAMA Internal Medicine, gives us a new opportunity which will make a real difference in clinical practice.

We all know about many individual risk factors identified at time of biopsy associated with prognosis in IgAN: these include clinical factors (proteinuria, GFR, blood pressure) and pathological factors (e.g. MEST-C score). But it has not been known how these individual factors add together to influence prognosis. Several attempts have been made to combine clinical and pathological risk factors, but these have often used pathological scoring which is not widely accepted, the cohorts have been small and of restricted ethnicity, and they have not been robustly validated.

The new IgAN Risk Prediction Tool deals with these challenges – an international partnership has combined large Caucasian, Japanese, and Chinese cohorts with sequential clinical data and MEST-C scores. Modelling has shown that the combination of demographic, clinical, and pathological factors is superior to the use of clinical factors alone, and is reliable independent of ethnicity.

The math of the risk formula is complex, so a web-based tool and an App are available – all that is needed to use the tool for an individual patient is some demographics, clinical risk factors at presentation (proteinuria, BP, eGFR, use of RAS blockade, use of immunosuppression) and the MEST score (the C, crescent score was tested but did not add to the model).

Some health warnings about the International IgAN Risk Prediction Tool:

  • Only use it with data available at the time of biopsy to predict risk up to 5 years from biopsy. Accuracy is less certain beyond 5 years as there were not sufficient long term data in the cohorts used

  • It was derived in adults and we are not sure yet if it applies to children

  • It has not been tested in IgA vasculitis

  • It should not be used to guide choice of immunosuppressive treatment

But we encourage you all to use it; and we are working to inform patients about it, so expect they will soon be asking you whether it applies to them.

Prof John Feehally,

Consultant Nephrologist at Leicester General Hospital and

Honorary Professor of Renal Medicine at the University of Leicester, UK.