African American vs Caucasian patients with a history of systemic lupus erythematosus (SLE) and venous thromboembolic (VTEs) events are less likely to have a clinically significant antiphospholipid antibody (aPL) profile, according to study results published in Arthritis Care & Research (Hoboken).
Recognizing that the risk for VTEs is increased in patients with SLE compared with the general population — attributed both to systemic inflammation and the presence of aPLs — the study authors sought to explore differences in aPL prevalence in Caucasian and African American patients with SLE and VTEs.
Data of African American and Caucasian patients with SLE and VTE events were obtained from the electronic medical record (EPIC) of a rheumatology practice based at an academic hospital between February 2016 and May 2019. A clinically significant aPL profile was defined as anticardiolipin immunoglobulin G/immunoglobulin M (IgG/IgM) and/or anti-β2 glycoprotein-I IgG/IgM of 40 or more units, and/or positive lupus anticoagulant (LA) of at least 1.3.
A total of 97 patients met the American College of Rheumatology (ACR) and/or 2012 Systemic Lupus Erythematosus International Collaborating Clinics (SLICC) classification criteria for SLE, had a history of VTE, and had available aPL tests. Of these patients, 59 were Caucasian and 38 were African American. Mean participant age was 48 years. Overall, 57% of patients (n=55) had a history of severe SLE, 37% (n=36) had a history of lupus nephritis, 30% (n=29) experienced recurrent VTE events, and 36% (n=35) had a clinically significant aPL profile.
A total of 47% of Caucasian patients vs 21% of African American patients had a clinically significant aPL profile (P =.01) Univariate logistic regression model showed that African American patients with SLE and VTE events had a 68% lower likelihood of having a clinically significant aPL profile compared with Caucasian patients (odds ratio [OR], 0.32; 95% CI, 0.12 to 0.80; P =.01). After adjustment for age, sex, Hispanic ethnicity, smoking status, and severe SLE, African American patients had a 66% lower likelihood of having a clinically significant aPL profile compared with Caucasian patients with SLE and VTE events (OR, 0.34; 95% CI, 0.12-0.96; P =.04).
According to Fisher’s exact test, a significant association was observed between type of aPL profile and race (P =.03). The presence of triple positivity was more common among Caucasian patients, while the majority of African American patients had a positive lupus anticoagulant test. At the time of a VTE event, African American patients had significantly higher levels of antidouble-stranded DNA (P =.02), lower hemoglobin levels (P =.01), and higher erythrocyte sedimentation rates (P =.008).
Study limitations included the retrospective design, small sample size, and missing data.
Study authors concluded that clinical evaluation of VTE risk in the African American population should rely more on traditional risk factors for VTE, as well as lupus-specific factors, such as disease activity and systemic inflammation. “Unlike Caucasians, where triple positivity is the dominant aPL phenotype in patients [with SLE] with VTE, [lupus anticoagulant] positivity even at low [to] moderate levels is the corresponding dominant aPL phenotype in [African American] patients [with SLE], and should be taken into account when assessing VTE risk,” they added.
Gkrouzman E, Peng M, Davis-Porada J, Kirou KA. Venous thromboembolic events in African American lupus patients are less likely associated with antiphospholipid antibodies compared to Caucasians. Arthritis Care Res (Hoboken). Published online November 10, 2020. doi:10.1002/acr.24508