Background/Purpose: In addition to the 1982 American College of Rheumatology criteria (ACR-82) for scientific classification of systemic lupus erythematosus (SLE), many clinicians find the ‘Fries criteria’ (requiring an abnormal ANA titer plus at least two typical organ manifestations) helpful for diagnostic purposes. Last year, the Systemic Lupus International Collaborating Clinics group proposed a new set of validated classification criteria (SLICC-12), claimed to being more sensitive for SLE. The aim of the present study was to analyze the performance of SLICC-12 compared to Fries criteria and ACR-82 among well-characterized SLE cases and controls in a regional Swedish register.

Methods: The study population consisted of 231 SLE cases (93% Caucasians; 203 women, 28 men; mean age at diagnosis 38.8 years, range 3-85) confirmed by Fries criteria and/or ACR-82. 53 controls (46 women, 7 men; mean age 40.8 years; range 12-83 years) were enrolled on the basis of referral to a rheumatology specialist based on at least one criterion regarding ‘immunologic disorder’ according to ACR-82 and a clinical suspicion of SLE. Sensitivity and specificity figures for SLE were calculated. All confirmed SLE cases took part in a prospective follow-up programme at the Rheumatology clinic, Linköping University hospital. Informed consent was obtained from all subjects and the research protocol was approved by the Regional Ethics Committee in Linköping (M75-08). The controls were eventually diagnosed with the following conditions: SLE, rheumatoid arthritis, palindromic rheumatism, undifferentiated arthritis, pleuritis, undifferentiated connective tissue disease, primary antiphospholipid syndrome, scleroderma, polymyositis, fibromyalgia, primary Sjögren’s syndrome, psoriatic arthritis, PAPA syndrome, renal infarction, mixed connective tissue disease, Muckle-Wells syndrome, arthralgia, multiple sclerosis and overlap syndrome.

Results: Of the confirmed SLE cases, 98% fulfilled Fries criteria, 81% ACR-82 and 91% SLICC-12. The combinations of Fries and/or SLICC-12 identified 99%, compared to 93% of all confirmed SLE cases identified by ACR-82 and/or SLICC-12. The sensitivity was high for Fries (97%) and SLICC-12 (91%), but lower for ACR-82 (79%), whereas the specificity was superior for ACR-82 (98%) compared to Fries (83%) and SLICC-12 (75%).

Conclusion: We confirm that the ACR-82 criteria set offers a very high diagnostic specificity, but fail to reveal >20% of the SLE cases as defined here. The SLICC-12 criteria provide important additional sensitivity, whereas the specificity was mediocre in this comparison. To increase sensitivity and specificity figures, we advice a combination of the ACR-82 and SLICC-12 criteria for future SLE studies.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/application-of-the-2012-systemic-lupus-international-collaborating-clinics-classification-criteria-on-a-regional-swedish-systemic-lupus-erythematosus-register/