Classification is important to help identify people to take part in research and ensures that similar disease states are included and compared in trials. This is different to tools that help clinicians make a diagnosis.
The APS classification criteria were last revised in 2006, but since then understanding of the disease has evolved. EULAR and ACR worked together to develop a new APS classification system based on modern disease understanding. The intention was that the new tool would also allow individual criteria and different risk profiles to be weighted and demonstrate excellent operating characteristics with the highest possible specificity.
After reductions and revisions, the updated classification specifies an entry criterion of at least one positive aPL test within 3 years of identification of an aPL-associated clinical criterion. This is followed by a set of weighted criteria, each scoring 1-7 points. The criteria are clustered into six clinical domains and two laboratory domains.
Related StoriesThe new classification criteria were tested in potential APS cases, with results showing good sensitivity and specificity. In fact, specificity for the new classification system was 99%, compared to 86% achieved with the original 2006 criteria. This is important, because classification criteria are based on standardized and stringent definitions to ensure consistency in clinical trials, and so very high specificity is required, even at the cost of sensitivity.