Session Type: ACR Poster Session A
Session Time: 9:00AM-11:00AM
Background/Purpose: Hypocomplementemia is common in systemic lupus erythematosus (SLE) and is included in classification criteria and disease activity indices. Whether persistently low complement levels (C3, C4 and both) are more important as serological markers, than levels which transiently drop in SLE is unknown. This work was undertaken to characterize SLE patients with persistent hypocomplementemia and to compare them to those with intermittently low levels.
Methods: Patients were identified as part of a longitudinal lupus cohort. Levels of C3 and C4 were measured quarterly, by nephelometry. Patients were considered with complement levels (either C3, C4 or both), which never returned to the normal range on longitudinal follow-up. Further analysis included those with intermittently low levels. To assess associated clinical manifestations, univariate and multivariate logistic regression were used. The multivariate analysis controlled for ethnicity, and gender.
Results: 2399 SLE patients, 53% Caucasian and 38% African-American, were evaluated. A history of ever having had low C3 was present in 55% and low C4 in 47%. There were 83 (4.0%) patients with persistently low C3, which never normalized and 65 (3.2%) individuals with persistently low C4. The clinical manifestations associated with persistent hypocomplementemia are outlined in Table 1 whilst those associated with transiently low levels are in Table 2. Persistently low C3 associates with renal, hematologic and serologic abnormalities with similar manifestations in those with intermittently low C3. Contrarily, chronically low C4 associates with a myriad of abnormalities, serologic and hematologic whilst intermittently low levels associate only with a positive anti-double stranded DNA, anticardiolipin and a false positive rapid plasma reagin. Persistently low C3 and C4 in combination associated with serologic abnormalities and the presence of antiphospholipid antibodies, whilst in those with transiently low levels there was cutaneous, neurologic, hematologic and immunologic dysfunction demonstrated.
Conclusion: Low complement is an important finding in SLE. Transiently low C4 is a weak marker which associates with few clinical manifestations. However, chronically low C4, which may represent a subset of patients with genetic deficiency, associates with a different spectrum of disease and has different, more severe, clinical implications.
To cite this abstract in AMA style:Durcan L, Fu W, Petri M. Unresolving C4 Hypocomplementemia Associates with a Different Spectrum of Disease in SLE and Is More Important Than Transiently Low Levels [abstract]. Arthritis Rheumatol. 2016; 68 (suppl 10). https://acrabstracts.org/abstract/unresolving-c4-hypocomplementemia-associates-with-a-different-spectrum-of-disease-in-sle-and-is-more-important-than-transiently-low-levels/. Accessed January 23, 2020.
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