By Sarah Tansley, MBChB, PhD
Editor’s note: Dr. Tansley was awarded a TMA research grant in 2022 for a pilot project to determine how the results of autoantibody tests vary when performed at different laboratories. This is a very important study that directly affects patient care. She recently completed this project and provides this report.
Blood tests that detect myositis-specific autoantibodies (MSA) are an important part of care for people with myositis. These tests help doctors understand how the disease might behave and whether someone may be at higher risk of complications such as lung disease or cancer. Getting accurate and reliable results is therefore essential for patients and their healthcare teams.
This research has shown that, at present, these blood tests do not always give the same results when they are performed in different laboratories. To study this, we shared the same blood samples from people with myositis with different laboratories around the world. Each laboratory tested the samples using their usual methods. When we compared the results, we found important differences.
Laboratories tested for different groups of autoantibodies, meaning that some could be missed. Even when the same autoantibodies were tested for, results were not always consistent. One particularly important finding was that the autoantibody “anti-Tif1γ” which is linked to an increased risk of cancer in adults with myositis was reported as negative by around one third of laboratories using a particular test, even though it was present in the sample. Other autoantibodies linked to lung disease were also sometimes missed.
These differences matter. Missing or incorrect results can make it harder for doctors to give clear advice at diagnosis, assess future risks, or tailor care to an individual. They could also affect research studies and clinical trials that aim to improve treatments for myositis.
As a result of this work, we are now focusing on improving testing for the autoantibodies that caused the most problems. An international group of doctors and laboratory specialists has been formed to develop clear guidance on how myositis autoantibody tests should be carried out, interpreted, and reported. This will help make results more consistent and easier to understand for both clinicians and patients.
Overall, this research aims to improve the accuracy of blood tests for myositis. By doing so, we hope to provide clearer information at diagnosis, better prediction of complications, and more personalized care for people living with myositis.