Autoantibodies as biomarkers for the prediction of neuropsychiatric events in systemic lupus erythematosus

Objective Neuropsychiatric events occur unpredictably in systemic lupus erythematosus (SLE) and most biomarker associations remain to be prospectively validated. This study examined a disease inception cohort of 1047 SLE patients to determine which autoantibodies at enrolment predicted subsequent neuropsychiatric events. Methods Patients with a recent SLE diagnosis were assessed prospectively for up to 10 years for neuropsychiatric events using the American College of Rheumatology case definitions. Decision rules of graded stringency determined whether neuropsychiatric events were attributable to SLE. Associations between the first neuropsychiatric event and baseline autoantibodies (lupus anticoagulant (LA), anticardiolipin, anti-beta(2) glycoprotein-I, anti-ribosomal P and anti-NR2 glutamate receptor) were tested by Cox proportional hazards regression. Results Disease duration at enrolment was 5.4 +/- 4.2 months, follow-up was 3.6 +/- 2.6 years. Patients were 89.1% female with mean (+/- SD) age 35.2 +/- 13.7 years. 495/1047 (47.3%) developed one or more neuropsychiatric event (total 917 events). Neuropsychiatric events attributed to SLE were 15.4% (model A) and 28.2% (model B). At enrolment 21.9% of patients had LA, 13.4% anticardiolipin, 15.1% anti-beta(2) glycoprotein-I, 9.2% anti-ribosomal P and 13.7% anti-NR2 antibodies. LA at baseline was associated with subsequent intracranial thrombosis (total n=22) attributed to SLE (model B) (HR 2.54, 95% CI 1.08 to 5.94). Anti-ribosomal P antibody was associated with subsequent psychosis (total n=14) attributed to SLE (model B) (HR 3.92, 95% CI 1.23 to 12.5, p=0.02). Other autoantibodies did not predict neuropsychiatric events. Conclusion In a prospective study of 1047 recently diagnosed SLE patients, LA and anti-ribosomal P antibodies are associated with an increased future risk of intracranial thrombosis and lupus psychosis, respectively.JGH was supported by Canadian Institutes of Health Research grant MOP-57752, Capital Health Research Fund. MBU's work was supported by the Canadian Institutes of Health Research (grant MOP-49529), the Lupus Foundation of Ontario, the Ontario Lupus Association, Lupus UK, the Lupus Foundation of America, the Lupus Alliance of Western New York, the Conn Smythe Foundation, the Lupus Flare Foundation and the Tolfo Family of Toronto, Ontario, Canada. LS was supported by MRC (UK) grant U.1052.00.009 and VF was supported by MRC (UK) grant U.1052.00.009. S-CB's work was supported by the Korea Healthcare technology R&D project, Ministry for Health and Welfare, Republic of Korea (A080588). The Montreal General Hospital Lupus Clinic is partially supported by the Singer Family Fund for Lupus Research. AC is a national scholar of the Fonds de la Recherche en Sante de Quebec. PRF is a distinguished senior investigator of the Arthritis Society, with additional support from the Arthritis Centre of Excellence, University of Toronto. RR-G's work was supported by the NIH (grants UL-1RR-025741, K24-AR-02318 and P60-AR-48098). GR-I is supported by the Department of Education, Universities and Research of the Basque Government