Background/Purpose: The effect of antiphospholipid antibodies (aPL) on organ damage in Systemic Lupus Erythematosus (SLE) patients remains unclear as there are limited number of studies with contrasting conclusions. The aim of this study was to assess the relative contribution of aPL to organ damage in SLE patients.

Methods: SLE patients (based on American College of Rheumatology [ACR] Classification Criteria) with less than 10 years of disease duration at registry entry were identified from an SLE registry. Clinical information retrieved included: demographics, disease duration, organ damage assessed by the Systemic Lupus International Collaborating Clinics/ACR Damage Index (SDI), and aPL profile. A “clinically significant” aPL profile was defined as: positive lupus anticoagulant test, anticardiolipin antibody IgG/M/A ≥ 40U, and/or anti-β₂Glycoprotein-I IgG/M/A ≥ 40U on two or more occasions, at least 12 weeks apart, within ± 1 year of registry entry. The outcome variable was any increase of SDI at 5 years of follow-up (time 0 was defined as registry entry). For univariate analysis the demographic and clinical characteristics of patients with and without a SDI increase at 5 years were compared (Chi square or Fisher’s exact test for categorical data, Student t test or Mann-Whitney for continuous data as appropriate). The Generalized Estimated Equations (GEE) model was used as multivariate analysis to detect significant factors for increased SDI at 5 years.

Results: Of 394 patients with less than 10 years of disease duration, 112 (28%) had at least 5 years of prospective follow-up and a complete aPL profile (44% Caucasian, 19% African-American, 15% Asian, and 89% female). Mean age at diagnosis was 32 years (±13) and mean age at registry entry was 35 years (±13) with mean disease duration of 3 years (±2). Twenty-one (19%) patients had clinically significant aPL profile (isolated IgA positivity only in 5 patients, 4%). Damage was present (SDI ≥ 1) in 18/112 (16%) of patients with a mean SDI of 1.9 (±1.7) at the registry entry, and in 27/112 (24%) at 5 years follow-up with a mean of 2.4 (±2.0). An increase of SDI (range: 1-5 points) after 5 years of follow-up was observed in 16/112 (14%) of patients. On a univariate analysis, no significant associations were found between any increase of SDI at 5 years and aPL profile, race, gender, age at diagnosis, and disease duration. The GEE model confirmed the lack of an association between the aPL profile and organ damage; African-American (Odds Ratio, [OR]: 7.58, 95% Confidence Interval, [CI]: 1.54-37.27, p: 0.013) and Asian (OR: 8.1, 95% CI: 1.49-44.16, p: 0.016) patients had significantly higher risk of increased SDI at 5 years.

Conclusion: Our preliminary data demonstrate that: a) approximately 15% of SLE patients have new organ damage in 5 years; b) one-fifth of SLE patients have clinically significant aPL profiles; and c) there is no association between organ damage and clinically significant aPL-profile.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-effect-of-clinically-significant-antiphospholipid-antibody-positivity-on-organ-damage-in-systemic-lupus-erythematosus/