Systemic lupus erythematosus in a multiethnic US cohort (LUMINA). XXIII. Baseline predictors of vascular events

Abstract

Objective: To determine the baseline (time 0) risk factors associated with the subsequent occurrence of vascular events in a multiethnic US cohort (LUMINA [LUpus in MInorities: NAture versus nurture]) of patients with systemic lupus erythematosus (SLE).

Methods: Five hundred forty-six LUMINA patients were assessed at time 0 for traditional and nontraditional (disease-related) risk factors for vascular events. These were defined as 1) cardiovascular (myocardial infarction and/or definite or classic angina and/or the undergoing of a vascular procedure for myocardial infarction [coronary artery bypass graft]), 2) cerebrovascular (stroke), and 3) peripheral vascular (arterial claudication and/or gangrene or significant tissue loss and/or arterial thrombosis in peripheral arteries). The observation time (followup time in the cohort) was the interval between time 0 and the last visit. The unit of analysis was the patient and not each vascular event. Variables at time 0 and vascular events were examined by univariable and multivariable (logistic and Cox proportional hazards regression) analyses. Age, sex, ethnicity, followup time, and all known risk factors for the occurrence of vascular events were included in the model.

Results: Thirty-four patients (6.2%) developed one or more vascular event after time 0. The overall median duration of followup in the cohort was 73.8 months (range 10.8-111.3 months). Vascular events (13 cardiovascular, 18 cerebrovascular, 5 peripheral vascular) occurred in 7 Hispanics from Texas (6.5%), 1 Hispanic from Puerto Rico (1.2%), 15 African Americans (7.5%), and 11 Caucasians (7.1%). The mean total number of traditional risk factors was significantly higher in patients who developed vascular events than in those who did not (7.1 versus 5.6). Independent predictors of vascular events were older age, current smoking status, longer followup time, elevated serum levels of C-reactive protein (CRP), and the presence of any antiphospholipid antibody. The same variables were identified when time-dependent analyses were performed, although azathioprine use was also found to be a contributing factor.

Conclusion: Smoking, previously not reported in SLE, emerged as a predictor of vascular events and should be strongly discouraged. Antiphospholipid antibodies and CRP support the role of inflammation and autoimmunity in the development of accelerated atherosclerosis in SLE. Ethnicity was not associated with vascular events in our patients.