GOTHENBURG, SWEDEN – Swedes with systemic lupus erythematosus tend to die early and at a substantially higher rate than does the general population.
During 13 years of prospective follow-up, 20% of 208 Swedish SLE patients died at a mean age of 60 years. That translates into an age-adjusted 3.3-fold increased rate of all-cause mortality, Dr. Elisabet Svenungsson reported at the annual congress of the European Academy of Dermatology and Venereology.
Cardiovascular disease accounted for 52% of the deaths, a proportion similar to what's seen in the general population. The difference is that cardiovascular death in the SLE cohort occurred predominantly in women at a substantially younger age than is common in women without SLE, observed Dr. Svenungsson, a rheumatologist at Karolinska University Hospital in Stockholm.
In addition to cardiovascular disease, patients with SLE have a number of other comorbidities, including osteoporosis, Sjögren's syndrome, and autoimmune thyroid disease, she reported.
Vascular disease is one of the most common of the many comorbidities associated with SLE, she noted. In a cross-sectional study of 597 patients in the Swedish SLE Network, 11% had ischemic heart disease, 10% had ischemic cerebrovascular disease, and 16% had a history of venous thromboembolism.
The conventional Framingham risk factors don't explain the accelerated atherosclerosis present in patients with SLE. In a prospective cohort study involving 182 SLE patients with a mean age of 44 years, all of whom were free of known cardiovascular disease at baseline, Dr. Svenungsson and coworkers found that the incidence of a first cardiovascular event was 13% during a mean 8.3 years of follow-up. In an age-adjusted, Cox multivariate regression analysis, the only conventional risk factors independently associated with a first cardiovascular event were smoking and age. Smokers with SLE were 2.6-fold more likely to experience an event than were nonsmokers. The risk rose 2.4-fold per 10 years of age.
The other independent predictors of a first cardiovascular event were the presence of any positive antiphospholipid antibody test, which conferred a 4.2-fold increased risk; an elevated von Willebrand factor level, associated with a 2.0-fold risk; and the presence of thrombocytopenia, which was a protective factor associated with a 65% reduction in the risk of a cardiovascular event, Dr. Svenungsson said in her keynote lecture at the meeting of the European Society of Cutaneous Lupus Erythematosus, which was held in conjunction with the EADV congress.
Multiple studies have established that one or more antiphospholipid antibodies are present in 30%-50% of SLE patients. Among a cohort of 320 SLE patients who were being followed by Dr. Svenungsson and her associates, 18% fulfilled strict 2006 criteria for antiphospholipid syndrome. SLE patients with antiphospholipid syndrome have a high rate of thrombotic events that don't track with SLE disease activity.
"They just hit here and there; you never really know when," she said.
Turning to osteoporosis and SLE, Dr. Svenungsson cited a new cross-sectional study by physicians at the University of Gothenburg, who obtained x-rays of the thoracic and lumbar spine in 150 women with SLE who had a median age of 47 years and disease duration of 11 years. Although 29% of the SLE patients had at least one radiologic vertebral compression fracture, only 4% had been diagnosed with a compression fracture.
"You have here a lot of women with a subclinical history of vertebral fractures. That we don't detect most of these fractures may be one reason why patients with SLE often complain about pain," according to Dr. Svenungsson.
In the Gothenburg study, advanced age was an independent risk factor for one or more vertebral fractures at any site, whereas low bone mineral density in the total hip was associated with vertebral fracture in the lumbar spine. Interestingly, cumulative glucocorticoid dose wasn't predictive of vertebral fracture risk (Arthritis Res. Ther. 2010 Aug. 2 [doi:10.1186/ar3104]).
A number of autoimmune diseases commonly overlap with SLE. Among them is autoimmune thyroid disease, which was present in 17% of 331 SLE patients being followed by Dr. Svenungsson and her associates at Karolinska, compared with 8% of matched controls. Hypothyroidism was far more common than hyperthyroid disease in the Karolinska cohort, as has been reported in other SLE studies.
Another autoimmune disease commonly overlapping with SLE is Sj?gren’s syndrome. In the Karolinska cohort, 25% of SLE patients met strict diagnostic criteria for Sjögren's syndrome. Dry mouth was reported by 40% of patients, compared with 7% of matched controls. Dry eyes were reported by 32% of SLE patients vs. 7% of controls.
In addition to cardiovascular disease, osteoporosis, Sjögren's syndrome, antiphospholipid syndrome, and autoimmune thyroid disease, other conditions that occur at an increased rate in patients with SLE include malignancies, rheumatoid arthritis, systemic sclerosis, myositis, vasculitis, autoimmune hepatitis, and infections.