Objectives The aim of our prospective study was to evaluate the role of antiphospholipid antibodies (aPL) on the clinical presentation of giant cell arteritis (GCA).
Methods GCA patients diagnosed for the first time between 1. September 2011 and 31. December 2016 at our secondary/tertiary rheumatology center and in whom aPL-Abs were determined at presentation were included. We studied four types of aPL-Abs in patient's sera: lupus anticoagulants (LA), IgG and IgM isotype of anticardiolipin antibodies (aCL), of antibodies to β2-glycoprotein 1 (aβ2GP1) and of antibodies to phosphatidylserine-prothrombin complex (aPS/PT). LA activity was determined only in patients not receiving anticoagulant therapy. A dilute Russell viper venom time test was used and a ratio above 1.2 was considered positive. aCL, aβ2GPI and aPS/PT were measured using an in-house ELISA. A value above the 99th percentile of healthy control population was taken as positive.
Results During the 64-month observation period we performed all aPL-Abs tests in 121 GCA patients (81 females (66.9%); median (IQR) age 73.8 (66.4; 78.7) years). We found LA, aCL, aβ2GP1 and aPS/PT in 59 (48.8%), 55 (45.5%), 15 (12.4%) and 18 (14.9%) cases, respectively. Fifty-four patients (44.6%) were single, 25 (20.7%) double, 13 (10.7%) triple and 1 (0.8%) quadruple aPL-Abs positive. 28 patients (23.1%) were aPL-Abs negative. Clinical characteristics of individual aPL-Ab type groups are presented in Table 1. There was one case of concurrent venous thrombotic event in our group (in a patient without aPL-Abs). The presence of aCL was associated with extracranial large vessel vasculitis (RR 1.8 (95% CI 1.1–2.9)). Double- or triple-positivity for any combination of “classic” aPL (LA and/or aCL and/or abeta2GP1) emerged as a marker of severe visual manifestations (RR of 2.1 (95% CI 1.1–4.3) for permanent or transient visual loss in case of double or triple aPL positivity vs. LA, aCL and aβ2GP1 negative cases). At least 1 year follow-up data (median (IQR) of 103 (54; 105) weeks) were available for 73 patients. 32 patients (43.8%) relapsed, most frequently those with positive aβ2GP1 (62.5%).
Conclusions Our results indicate that aCL could identify GCA patients with extracranial large vessel disease. The double- or triple-positivity for any combination of LA and/or aCL and/or aβ2GP1 seems to be a marker of severe visual manifestations.
Disclosure of Interest None declared