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SAN DIEGO — The European League Against Rheumatism (EULAR) and the American College of Rheumatology (ACR) have collaborated to establish new classification criteria for systemic lupus erythematosus (SLE), as presented at the 2017 ACR/ARHP Annual Meeting in San Diego, California.
In the past, investigative groups have favored either the EULAR or ACR criteria, making comparison of the results of various studies challenging.
“In the last 10 to 15 years, the standards for development of classification criteria have changed,” said Sindhu Johnson, MD, PhD, director of the Toronto Scleroderma Program at the University of Toronto. “We have come to appreciate potential biases that may reduce the validity or reliability of classification criteria, and as a consequence, both organizations have put out position papers on the standards we must consider when we develop classification criteria.”
As a result, Dr Johnson said, EULAR and ACR jointly funded and collaborated on creating a set of criteria that can be used to more accurately identify patients with SLE for inclusion in clinical trials.
The Process of Creating a New Set of Criteria
The process to establish a new set of criteria was conducted in 4 phases over the past 4 years:
Phase 1 involved item identification. Antinuclear antibody was found to have high sensitivity but low specificity in identifying lupus; therefore, more criteria were needed. Using 4 studies, 144 candidate criteria were nominated. A cross-sectional survey of patients with lupus was also conducted, in which patients were asked about early symptoms of the disease.
Phase 2 reduced these 144 candidate criteria down to 40 items. Phase 3 then weighted items and identified thresholds. “We realize that not all criteria are equal. Using a process called multi-criteria decision analysis, we were able to identify differential weighting for different criteria,” Dr Johnson said.
Phase 4 involved fine tuning and final validation of this body of work. The criteria were tested on 500 patients with SLE from 36 lupus centers and 500 controls.
“When we tested the performance of this draft proposal, we found a sensitivity of 98% and a specificity of 97%,” Dr Johnson said. Compared with previous classifications of lupus, sensitivity was improved, and excellent specificity was maintained.
What Does the New Criteria System Look Like?
“Right now, we have an entry criterion of an antinuclear antibody titer of 1:80 by immunofluorescent testing If a patient has that, additive criteria — including clinical domains and immunologic domains — are considered,” Dr Johnson said. “Within these domains, there are subdomains weighted from lowest to highest. Within any one domain, only the criterion with the highest score may be counted. If a patient has a score of 10 or more, they may be classified as having systemic lupus erythematosus.”
Through a multiphase program with both expert-based and data-driven methods, including patient perspective, a system of criteria has been defined that measures a relative probability that a particular patient with a combination of clinical symptoms and features has lupus. “The differential weighting more accurately reflects our current understanding of the disease,” Dr Johnson said.
This global effort included data on more than 3500 subjects, in addition to the 20,000 subjects in the systematic review, and included more than 189 investigators.
Dr Johnson also noted that a unique aspect of these new criteria is that there will now be patients who score just under the threshold for lupus, such as those with a score of 8 or 9. This prompts such questions as, “What do we call these patients? Is this considered early disease? Could this raise the possibility of prevention studies?”
The next 2 weeks will consist of an open consultation process. Those with feedback can contact Dr Johnson or Martin Aringer, MD, who are representing EULAR at the ACR/ARHP 2017 Annual Meeting. Dr Johnson anticipates the final validation of these criteria to be presented at the EULAR annual meeting in June 2018.
Johnson S. European League Against Rheumatism and American College of Rheumatology present new SLE classification criteria at the 2017 ACR/ARHP annual meeting. Presentation at: ACR/ARHP 2017 Annual Meeting; November 3-8, 2017; San Diego, CA.