Findings presented at the EULAR 2026 Congress have shed new light on idiopathic inflammatory myopathies (IIM), a group of rare autoimmune muscle diseases, revealing significant differences in disease occurrence across sex and ethnic groups and introducing a promising new method for monitoring disease activity.
Idiopathic inflammatory myopathies are a heterogeneous group of autoimmune disorders characterized by chronic muscle inflammation, weakness, and substantial long-term disability. Although classification criteria developed jointly by EULAR and the American College of Rheumatology have improved disease identification, real-world data on disease burden and activity assessment remain limited.
Rising Cases Linked to Demographic Changes
In one of the largest population-based studies of its kind, researchers analyzed data from England spanning nearly two decades (2002–2021). The study identified 4,105 patients diagnosed with dermatomyositis, inclusion body myositis, or other forms of IIM, including polymyositis.
The findings showed that the number of diagnosed cases increased considerably over the study period. However, age-standardized incidence rates remained largely stable, suggesting that population aging rather than a true increase in disease occurrence may be responsible for the rising numbers.
Researchers also observed clear differences among disease subtypes. Women experienced higher rates of dermatomyositis and other inflammatory myopathies, while men were more frequently affected by inclusion body myositis.
Significant ethnic disparities were also identified. Individuals of South Asian, Black, and mixed ethnic backgrounds demonstrated a higher incidence of certain IIM subtypes compared with white populations. Researchers emphasized that additional studies are needed to determine whether these patterns reflect genuine biological differences or variations in healthcare access, diagnosis, and disease recognition.
Presenting the findings at EULAR 2026, lead investigator Patrick Gordon noted that the study provides valuable insights into how inflammatory myopathy subtypes vary across demographic groups and throughout different stages of life.
Automated Imaging Outperforms Traditional Blood Tests
A second study presented at the congress focused on improving disease activity assessment in inflammatory myopathies.
Currently, physicians commonly rely on blood markers such as muscle enzymes, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) to evaluate disease activity. However, these biomarkers do not always accurately reflect a patient's clinical condition.
Researchers from the CapIAMI group investigated the use of automated quantitative nailfold videocapillaroscopy (NVC), a non-invasive imaging technique that visualizes small blood vessels near the fingernails and can detect microvascular inflammation.
The team developed several predictive models incorporating NVC measurements and laboratory biomarkers. Among all approaches tested, the combined NVC and laboratory model delivered the best performance, achieving a sensitivity of 60.2% and specificity of 83.3%.
Importantly, the NVC-only model significantly outperformed models based solely on conventional laboratory biomarkers, demonstrating that microvascular imaging provides valuable disease activity information not captured by standard blood tests.
Researchers found that specific NVC parameters, including capillary patterns and the proportion of normal capillaries, were the strongest independent predictors of disease activity. Traditional biomarkers contributed comparatively little additional information.
The study reported a positive predictive value of 91.4%, suggesting that quantitative NVC may help clinicians confidently identify active disease and make treatment decisions even when laboratory results are inconclusive.
Potential Shift in Clinical Practice
The findings support the growing role of advanced imaging technologies in autoimmune disease management. Investigators believe automated quantitative nailfold videocapillaroscopy could become an important component of routine monitoring for patients with inflammatory myopathies.
While further validation is required, the research suggests that integrating microvascular imaging into clinical practice may improve disease assessment and help physicians tailor treatment strategies more effectively.
Together, these studies provide important new insights into the epidemiology of inflammatory myopathies and highlight innovative tools that could enhance patient care in the future.
