The risk of venous thromboembolism increases markedly shortly before the diagnosis of giant cell arteritis regardless of glucocorticoid exposure, peaks at the time of diagnosis, and then progressively declines, according to a matched cohort review involving more than 6,000 arteritis patients.
It’s not been clear until now if the recently recognized risk of venous thromboembolism (VTE) in giant cell arteritis (GCA) was due to the disease itself, or the glucocorticoids used to treat it. “Because inflammation in GCA spares the venous circulation, our finding that patients are at greatest risk of VTE in the period surrounding GCA diagnosis (when inflammation is at its highest level), and the demonstration that this risk is not associated with the use of glucocorticoids, suggest that immunothrombosis could play a pathogenic role,” said investigators led by Sebastian Unizony, MD, of Massachusetts General Hospital, Boston (Arthritis Rheumatol. 2017 Jan;69[1]:176-84).
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The report was short on advice about what to do to prevent VTE in GCA, but the investigators did recommend “adequate monitoring ... for early recognition of this potentially serious complication.”
The team used a British medical record database covering 1990-2013 to compare 6,441 patients with new-onset GCA to 63,985 controls without GCA matched for age, sex, and date of study entry. VTE was defined as pulmonary embolism and/or deep vein thrombosis.
The incidence of VTE shortly before diagnosis was 4.2 cases per 1,000 person-years in the GCA group, but 2.3 cases per 1,000 person-years among controls. It was about the same when the analysis was limited to GCA patients not exposed to oral glucocorticoids before diagnosis: 4.0 cases versus 2.2 cases in the control group per 1,000 person-years. The finding was key to the conclusion that GCA is an independent VTE risk factor.
During the 12, 9, 6, and 3 months leading up to GCA diagnosis, the relative risks for VTE among patients not treated with glucocorticoids – versus controls – were 1.8, 2.2, 2.4, and 3.6. In the first 3, 6, 12, 24, 48, and 96 months after GCA diagnosis, when virtually all patients were on glucocorticoids at least for the first 6 months, the relative risks for VTE were 9.9, 7.7, 5.9, 4.4, 3.3, 2.4; the last risk score of 2.4 indicated that GCA patients were still slightly more likely than controls to have a VTE even 8 years after diagnosis.
The mean age of patients in the study was 73 years, and 70% of the subjects were women. GCA patients were more likely than were controls to be smokers and to have cardiovascular disease. Also, a greater proportion of GCA patients used aspirin and had recent surgery and hospitalizations. There was no difference in body mass index (mean in both groups 27 kg/m2) or the prevalence of fracture, trauma, or cancer between the groups.
The National Institutes of Health funded the work. There was no disclosure information in the report.