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Abstract
Background Discoid lupus erythematosus (DLE) progresses to systemic lupus erythematosus (SLE) in up to 28% of cases. The 2012 Systemic Lupus International Collaborating Clinics (SLICC) criteria were developed to improve the American College of Rheumatology (ACR) criteria. So far, the SLICC criteria have not been evaluated in DLE.
Methods This is a case-control study comparing patients with DLE who meet ACR and/or SLICC criteria for SLE against patients with DLE-only disease. The data was obtained from an ongoing database with 142 DLE patients at Penn and from their respective medical records.
Results Using the ACR criteria, 75 (53%) patients were classified as DLE/SLE and 67 (47%) as DLE-only, compared with 66 (47%) DLE/SLE and 76 (53%) DLE-only patients using the SLICC criteria (p = 0.08). This net increase of eight patients meeting ACR criteria was due to the presence of the photosensitivity criterion and fewer immunologic criteria under ACR. Due to the immunologic criteria requirement under SLICC, it can be challenging to determine an SLE diagnosis retrospectively. Overall, DLE/SLE patients were more likely than DLE-only patients to exhibit hematologic and immunologic criteria with respect to leukopenia (ACR p < 0.0001; SLICC p < 0.0001), + anti-dsDNA (ACR p < 0.0001; SLICC p < 0.0001), and + ANA (ACR p < 0.0001; SLICC p < 0.0001) under both criteria. Furthermore, DLE/SLE patients were more likely than DLE-only patients to exhibit significant systemic symptoms with regard to arthritis (ACR 72% vs. 9%, p < 0.0001; SLICC 70% vs. 18%, p < 0.0001), serositis (ACR 21% vs. 0%, p < 0.0001; SLICC 22% vs. 3%, p < 0.0001), renal disorder (ACR 27% vs. 2%, p < 0.0001; SLICC 33% vs. 0%, p < 0.0001) using both criteria. DLE/SLE patients were more likely to have worse skin disease compared to DLE-only patients when classified according to the ACR criteria, with 40.8% of DLE/SLE patients having CLASITM activity ≥ 10 and 24.2% of DLE-only patients having CLASITM ≥ 10 (Table 1).
Skin activity in DLE/SLE vs DLE-only patients using ACR criteria. DLE/SLE patients are more likely to have worse skin disease compared to DLE-only patients when classified according to the ACR criteria
Skin activity in DLE/SLE vs DLE-only patients using SLICC criteria. There is a trend of DLE/SLE patients having worse skin disease compared to DLE-only patients when classified according to the SLICC criteria
Conclusion These findings suggest that DLE patients who meet SLE criteria are more likely than their DLE-only counterparts to have more significant internal disease. Both ACR and SLICC criteria are useful in distinguishing DLE patients with internal organ involvement from those without. DLE-only patients may have significant skin disease with 25% of DLE-only patients having moderate to severe skin disease.