Background Systemic Lupus Erythematosus (SLE) is an autoimmune disease in which inflammation is mediated by complement activation by immune complex deposit, leading to damage. Consumption of C3 and C4 complement fragments is accepted as a disease activity marker.
The aim ofthis study is to describe clinical and serologic characteristics of SLE patients according to complement levels.
Methods Our SLE electronic database was analyzed (Jan 2014–Aug 2016). We included patients 18 years, fulfilling ACR 1997/SLICC 2012 classification criteria, with at least one year follow-up and at least two complement levels determinations at different times during follow-up.
Patients were classified in 4 groups, defined as following: Group 1 (normal C3 and C4 on all determinations), Group 2 (C3 and C4 below reference levels on all determinations), Group 3 (only C4 below reference levels on all determinations) and Group 4 (C3 and/or C4 on variable levels, with at least one determination below reference levels).
Demographic data, disease activity by SELENA-SLEDAI, accrual damage by SLICC-DI, presence of anti DNAds and anti Sm antibodies and clinical manifestations were assessed.
Statistical analysis was performed using Epi info v7. Correlation was assessed using chi2 or Fisher’s test appropriate.
Results 149 patients were included. 95.3% female, mean age at diagnosis was 30.6 years (CI: 28,5 32,8), mean disease duration 9.7 years. Mean SLICC-DI by group: Group 1 1.0, Group 2 0.5, Group 3 1.3 and Group 4 0.6.
All groups with hypocomplementaemia showed a higher SLEDAI respecting Group 1 (p=0.0013)(table 1)
Presence of anti DNAds and anti Sm antibodies is shown in table 1.
Respecting clinical manifestations, a significant difference was found in Lupus Nephritis (Group 1 36.8%, Group 2 44.1%, Group 3 78.6% and Group 4 36,4% (p=0.0002)) and hemolytic anemia (Group 3 28.6% and Group 1 17.6% (p: 0.0196))(table 1).
Conclusions An association between C4 persistently below reference levels (Group 4) and anti DNAds antibodies and Lupus Nephritis was found. Group 3 patients may have a worse prognosis due to renal involvement.
Complement levels during follow up could be used as a marker to assess nephritis risk in SLE patients.
Funding Source(s): None
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