EULAR develops first classification criteria for hemochromatosis arthropathy

EULAR - The European Alliance of Associations for Rheumatology - has developed the first classification criteria for hemochromatosis arthropathy (HA) from a unique derivation cohort using rigorous methodology.

HA is distinctive arthropathy associated with genetic hemochromatosis - a condition where iron levels build up over time. This has many consequences, including liver cirrhosis, diabetes, and a distinctive arthropathy. Cases are most often reported in people with high ferritin and the C282Y homozygous mutation in the HFE gene. But at present, there is a knowledge gap around the pathogenesis, and more information is needed about the link between gene mutations, hepcidin deficiency, iron loading, and joint disease. Of note, there are no classification criteria for HA, and this has limited research into this arthropathy.

To address these gaps, EULAR put together a task force of healthcare professionals and patient research partners. The project had three phases, designed to review the features of HA and create possible classification criteria, before testing these in people with known HA - as well as in a control group of people with other diseases that look very similar, such as generalised osteoarthritis and calcium pyrophosphate deposition disease.

The result was a points-based classification model that can be used in people with joint pain, plus the C282Y homozygous HFE mutation and past evidence of iron loading. The model uses eight variables that cover age at symptom onset, clinical and radiographic features at the metacarpophalangeal, distal interphalangeal, and ankle joints, and history of surgery at the hip or ankle. Each of these items is easily assessed in routine clinical practice, and together they are thought to be the best discriminators versus disease mimics. To achieve the threshold a person must score at least 5 out of 11, across a minimum of three criteria. This approach, which represents the first classification criteria designed to be used in this group of people, provides 93.3% specificity and 71.4% sensitivity for classifying to HA.

We are delighted to have produced the first classification criteria for this much neglected and poorly understood arthropathy. Our hope is that this will stimulate renewed academic interest and good quality trials to advance our understanding of this condition - and ultimately to develop new treatments to stop the progression of joint disease in these people."

Patrick Kiely, lead author on the paper and Professor of Clinical Practice in Rheumatology at St George's University Hospital, London, UK

The criteria are not diagnostic, and should only be used to recruit patients for research studies. Although external validation in separate cohorts is still needed, EULAR hopes this development will raise awareness and stimulate interest and research - and ultimately support new treatment options for patients in the future.