Subclinical atherosclerosis in systemic lupus erythematosus (SLE): the relative contribution of classic risk factors and the lupus phenotype

OBJECTIVES: We aimed to examine the strength of association between traditional cardiovascular risk factors and carotid plaque development in systemic lupus erythematosus (SLE) patients and controls. We also aimed to determine which lupus-related factors are associated with carotid plaque and whether SLE sensitizes patients to the effects of traditional factors. METHODS: We studied 200 women with SLE and 100 controls. Demographic and risk factor data were collected and SLE features, including autoantibody profiles and therapy were noted. All subjects had B- mode ultrasound of their carotid arteries examined for the presence and distribution of plaque. RESULTS: SLE patients <55 years old had more plaque (21% vs 3% P < 0.01) and more SLE patients had plaque in the internal carotid artery (11% vs 4%; P < 0.05). Traditional risk factor models performed less well in SLE compared with controls [area under Receiver Operator Characteristic curves (AUC ROC) = 0.76 vs 0.90; P < 0.01]. A multivariable model using SLE factors only, performed significantly better (AUC ROC = 0.87; P < 0.01). The final model in SLE included age and cigarette pack-years smoking as well as azathioprine exposure ever, antiphospholipid antibodies (APLA) and previous arterial events (AUC ROC = 0.88). CONCLUSIONS: SLE patients have a higher prevalence and different distribution of carotid plaque than controls. SLE factors perform significantly better than traditional risk factors in their association with atherosclerosis in SLE and these factors add to the influence of traditional risk factors rather than sensitizing lupus patients to traditional factors. The SLE phenotype helps identify patients at increased risk of atherosclerosis.