International study sets new standards for arthritis ultrasound diagnosis

People with early inflammatory arthritis could benefit from faster and more accurate diagnosis following a major international study that has established, for the first time, age-specific ultrasound standards to distinguish normal joint changes from the earliest signs of disease.

Published in Lancet Rheumatology, the research analysed more than 28,000 joints from 802 healthy volunteers across 13 countries and developed new ultrasound reference values based on both age and joint type. The findings are expected to help clinicians identify inflammatory arthritis more confidently, reducing the risk of both delayed diagnosis and unnecessary treatment

Researchers from the University of Birmingham supported by the National Institute for Health and Care Research (NIHR) Biomedical Research Centre (BRC): Birmingham played a leading role in the study, working alongside international collaborators.

Professor Andrew Filer said: "Early diagnosis is critical in inflammatory arthritis because prompt treatment can prevent irreversible joint damage and substantially improve long-term outcomes for patients.

"Ultrasound has become an increasingly important tool in rheumatology, but until now we lacked robust international reference standards that reflected what is normal at different ages and in different joints. This study provides that evidence base.

"By establishing clear thresholds for normal and abnormal findings, we can give clinicians greater confidence when assessing patients with suspected inflammatory arthritis and help ensure that people who need treatment are identified as early as possible."

The international project was conducted through the OMERACT (Outcome Measures in Rheumatology) Ultrasound Working Group and jointly led by Professor Andrew Filer, Professor of Translational Rheumatology at the University of Birmingham and Director of the NIHR BRC: Birmingham, and Professor Maria Antonietta D'Agostino from Università Cattolica del Sacro Cuore and Fondazione Policlinico Universitario Agostino Gemelli IRCCS in Rome.

The work builds on previous OMERACT ultrasound research that established internationally agreed definitions and scoring systems for ultrasound-detected synovitis in rheumatoid arthritis, helping to standardise the use of ultrasound in both clinical practice and research.

Understanding what is normal

The multicentre observational study involved healthy participants aged between 18 and 80 years, recruited from 20 centres across Europe, South America, Asia and the Middle East. Researchers set out to address a longstanding challenge in rheumatology: understanding which ultrasound findings represent normal variations in healthy people and which indicate genuine inflammatory disease.

Participants underwent detailed ultrasound examination of joints in the hands, wrists and feet. Researchers assessed three key features associated with inflammation: synovial hypertrophy, Doppler signal and joint effusion. Of the more than 28,000 joints examined, 13% showed abnormalities above grade 0, with the highest prevalence seen in the first and second metatarsophalangeal joints of the foot.

Dr Ilfita Sahbudin, Associate Professor of Rheumatology at the University of Birmingham and first author of the paper said: “This has been a global effort to create a reference for clinicians to see what ‘normal’ looks like across the widest diversity of patients possible. The resulting reference guide is a hugely important guide, with a significant dataset to support better diagnostic use of ultrasound.”

Supporting earlier and more accurate diagnosis

One of the study's most important findings was that the presence of a Doppler signal, which indicates increased blood flow commonly associated with inflammation, should always be considered abnormal in the joints examined, regardless of a person's age. By contrast, normal levels of synovial hypertrophy and joint effusion varied according to both age and joint location, highlighting the need for age-specific reference values.

Professor Maria Antonietta D'Agostino from Università Cattolica del Sacro Cuore and Fondazione Policlinico Universitario Agostino Gemelli IRCCS said: "When we perform an ultrasound to assess for synovitis or arthritis, small changes in the synovial membrane may already be present even in healthy individuals.

"Our goal was to identify findings that are highly specific for early inflammatory disease and whose presence can reliably indicate arthritis, particularly in people considered at risk, such as those with autoantibodies or persistent inflammatory pain.

"We found that Doppler abnormalities, reflecting increased blood flow in the synovial membrane, should always be regarded as pathological. Likewise, abnormalities affecting certain joints, such as the small joints of the hands, should always be considered pathological regardless of age, even when patients have not yet developed clinical symptoms."

Key role for volunteers

A key contribution to the study came from the Birmingham 1000 Elders Group, a University of Birmingham volunteer research cohort that enables healthy older adults to participate in studies investigating ageing and age-related disease.

Data from this group helped researchers understand which ultrasound findings represent normal age-related changes and which are more likely to indicate underlying inflammatory disease.

Professor Filer added: “This impactful research highlights the value of international collaboration, alongside the translational research infrastructure provided by the University of Birmingham, the NIHR Biomedical Research Centre: Birmingham, Birmingham Tissue Analytics and the Birmingham Healthy Elders Cohort.”