New blood test for rheumatoid arthritis

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October 23, 2017

Researchers at Fiona Stanley Hospital (FSH) and PathWest have discovered a simple blood test that can predict the risk of serious infection in rheumatoid arthritis patients.

Rheumatoid arthritis is an autoimmune disorder believed to stem from the immune system attacking the body’s own tissues, particularly bones and joints. Accordingly, many of the more commonly prescribed treatments work by suppressing the immune system.

These treatments, such as corticosteroids (prednisolone), help relieve patients’ symptoms but also make them vulnerable to serious infection.

The test involves measuring mannose binding lectin (MBL) – a serum protein involved in immune defence. Low concentrations of MBL have been associated with infections, particularly in children where the immune system is not fully developed.

FSH rheumatologist and Associate Professor of Medicine at the University of Notre Dame Dr Graeme Carroll and his research team looked at the factors which make serious infection more likely in a group of rheumatoid arthritis patients over an average six years.

What they found surprised even them.

“We’ve known about the existence of MBL for some time, but we were not expecting such a significant link between the amount of MBL and the likelihood of serious infection,” said Dr Carroll.

“Essentially, this is the first study that has identified undetectable MBL as an important risk factor for serious infections in rheumatoid arthritis patients.”

Data was collected from 228 patients including the type of treatment used for rheumatoid arthritis, age, other medical problems, smoking history, antibody levels and MBL concentrations. The frequency and type of serious infections was assessed, with researchers finding undetectable MBL concentrations in 15 per cent of participants. One in 6 participants developed at least one serious infection over the course of the study.  

Of all the risk factors for serious infection that were assessed, only increased age, corticosteroid use and undetectable MBL concentrations were associated with significant increased risk of serious infection.

“We know that if you have rheumatoid arthritis, you have an increased risk of serious infection,” Dr Carroll said.

“But if you also have undetectable MBL, then you are at greater risk.

“If you happen to have undetectable MBL and also require corticosteroids, you are at greater risk still.

“Such patients have a 10-fold higher risk for serious infection.”

Dr Carroll said this information could play an important part in designing current and future treatment plans.

“Now that we can identify patients with undetectable MBL, we can tailor their treatment accordingly, which should help prevent some serious infections and lead to better overall health and wellbeing.”

The study was recently published in The Journal of Allergy and Clinical Immunology: In Practice (JACI IP).