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MADRID—Systemic lupus erythematosus (SLE) experts in North America and Europe are working together to refine the classification system for the disease, with the goal of producing a new set of criteria that is simpler to use and more scientifically rigorous than any classification approach previously published, speakers involved with the process said at the 2017 Annual European Congress on Rheumatology (EULAR).
The system, a joint effort between the ACR and EULAR, is slated to include criteria in clinical and immunological domains, and validation of draft criteria is ongoing. Presentations at the conference pointed to the challenges involved, and showed in detail the lengths to which the experts have gone to produce reliable criteria and how they’ve used technology as a critical tool.1
The nature of SLE makes it a notoriously difficult disease to classify, said Martin Aringer, MD, chief of rheumatology at University Medical Center Carl Gustav Carus in Dresden, Germany, who is helping lead the effort. “Multi-organ, multi-antibody disease is challenging for classification,” he said, speaking at a scientific session.
The 1982 ACR classification criteria, which were updated in 1997, require four of 11 criteria to be met for an SLE classification. These criteria have had great influence in the field over the past two decades. They promote the concept of the disease as multiple antibody and multiple organ, and put all the criteria on equal footing with equal weight, making it easy to use and memorize.
This approach has not been entirely intuitive, Dr. Aringer noted. Dermatologists, for example, have criticized that the criteria could be fulfilled by meeting the four mucocutaneous criteria. And the sensitivity has been considered suboptimal, at just 83% in the cohort of the SLE International Collaborating Clinics (SLICC) and lower in patients earlier in the disease course.
Under the 2012 SLICC criteria, patients have to be positive for anti-nuclear antibodies or antibodies to double-stranded DNA, and lupus nephritis on histology means automatic SLE classification.2 Sensitivity with these criteria is good, but specificity is below that of the ACR criteria. Dr. Aringer said that was likely because the SLICC group chose to keep the classification system structure similar to the previous system.
With this new effort, experts are trying to do better. “The main goals are to have a relatively intuitive set that helps in teaching; increase the sensitivity by comparison to the [current] ACR criteria, but maintain specificity in the same range; improve performance in early SLE; involve the larger SLE community as far as possible; and do this in a strictly scientific way,” Dr. Aringer said.
The Process
Sindhu Johnson, MD, PhD, a clinical researcher at University Health Network in Toronto, who is also helping lead the creation of the new system, described a rigorous, multilayered process of whittling down a list of criteria, literature review and organizing the criteria into seven clinical domains and three immunological domains.