Predictors of carotid atherosclerosis in systemic lupus erythematosus

Patients with systemic lupus erythematosus (SLE) are at increased risk for cardiovascular and cerebrovascular events, even after adjustment for traditional risk factors. We examined the association of traditional risk factors, novel markers of cardiovascular disease (C-reactive protein, homocysteine, lipoprotein(a), plasminogen activator inhibitor-1, fibrinogen), and markers indicative of SLE activity (including C3, C4, anti-dsDNA, and prednisone use) with the presence of significant plaque on carotid duplex imaging.

Six hundred five patients with SLE enrolled in the Hopkins Lupus Cohort Study (92% female, 38% African-American) underwent carotid duplex testing. Prospectively gathered clinical, laboratory, and serologic data from their quarterly followup visits in the Hopkins Lupus Cohort were used in the analyses. For predictors that varied over time, such as cholesterol, the mean values during cohort participation were calculated for the analysis. Informed consent was obtained from all patients.

The presence of carotid plaque was strongly associated with age, ranging from 1% among those less than 30 years of age to 61% among those 60 years or older. After adjusting for age, there were moderate or strong associations of carotid plaque with male gender (age-adjusted risk 25% vs 13%; p = 0.051), hypertension (age-adjusted risk 18% vs 8%; p = 0.0001), diabetes mellitus (age-adjusted risk 19% vs 13%; p = 0.075), C3 > 120 mg/dl (age-adjusted risk 18% vs 11% and 14% for normal and low C3, respectively; p = 0.046), serum creatinine > 1.3 (age-adjusted risk 32% vs 13%; p = 0.039), and mean systolic blood pressure > 140 (age-adjusted risk 23% vs 13%; p = 0.028). There was no strong evidence of an association between plaque and SLE disease activity (age-adjusted risk 14% among those with adjusted mean SLEDAI > 3 vs 14% among those with lower SLEDAI) or with time since SLE diagnosis (age-adjusted risk 12%, 14%, and 16% among those with SLE for < 2, 2-8, and > 8 years, respectively; p = 0.49).

Traditional cardiovascular risk factors were associated with carotid plaque in SLE. However, SLE disease activity and duration of SLE are not strongly associated with carotid plaque. A "lupus factor" separate from traditional risk factors remains unidentified.