Objective The aim of this study was to describe the frequency, attribution, outcome and predictors of seizures in systemic lupus erythematosus (SLE).
Methods The Systemic Lupus International Collaborating Clinics, or SLICC, performed a prospective inception cohort study. Demographic variables, global SLE disease activity (SLE Disease Activity Index 2000), cumulative organ damage (SLICC/American College of Rheumatology Damage Index (SDI)) and neuropsychiatric events were recorded at enrolment and annually. Lupus anticoagulant, anticardiolipin, anti-β2 glycoprotein-I, antiribosomal P and anti-NR2 glutamate receptor antibodies were measured at enrolment. Physician outcomes of seizures were recorded. Patient outcomes were derived from the SF-36 (36-Item Short Form Health Survey) mental component summary and physical component summary scores. Statistical analyses included Cox and linear regressions.
Results The cohort was 89.4% female with a mean follow-up of 3.5±2.9 years. Of 1631 patients, 75 (4.6%) had ≥1 seizure, the majority around the time of SLE diagnosis. Multivariate analysis indicated a higher risk of seizures with African race/ethnicity (HR (CI): 1.97 (1.07 to 3.63); p=0.03) and lower education status (1.97 (1.21 to 3.19); p<0.01). Higher damage scores (without neuropsychiatric variables) were associated with an increased risk of subsequent seizures (SDI=1:3.93 (1.46 to 10.55); SDI=2 or 3:1.57 (0.32 to 7.65); SDI≥4:7.86 (0.89 to 69.06); p=0.03). There was an association with disease activity but not with autoantibodies. Seizures attributed to SLE frequently resolved (59/78 (76%)) in the absence of antiseizure drugs. There was no significant impact on the mental component summary or physical component summary scores. Antimalarial drugs in the absence of immunosuppressive agents were associated with reduced seizure risk (0.07 (0.01 to 0.66); p=0.03).
Conclusion Seizures occurred close to SLE diagnosis, in patients with African race/ethnicity, lower educational status and cumulative organ damage. Most seizures resolved without a negative impact on health-related quality of life. Antimalarial drugs were associated with a protective effect.
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Ethics approval This study was conducted with the approval of the Capital Health Research Ethics Board, Halifax, NS, Canada.
Provenance and peer review Not commissioned; externally peer reviewed.
Funding JG Hanly was supported by Canadian Institutes of Health Research grant MOP-57752 (Capital Health Research Fund). Li Su was supported by MRC (UK) U105261167. V Farewell was supported by MRC (UK) U105261167. Dr Sang-Cheol Bae'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 was partially supported by the Singer Family Fund for Lupus Research. Dr Clarke is a National Scholar of the Fonds de la recherché en santé de Quebec. Dr Paul R. Fortin is a Distinguished Senior Investigator of The Arthritis Society with additional support from the Arthritis Centre of Excellence, University of Toronto. Dr Ramsey-Goldman's work was supported by the National Institutes of Health (grants UL-1RR-025741, K24-AR-02318 and P60-AR-48098). Dr Ruiz-Irastorza was supported by the Department of Education, Universities and Research of the Basque Government.
Competing interests None.