Background/Purpose: Studies indicating a higher incidence rate of stroke and venous thromboembolism (VTE) among patients with giant cell arteritis (GCA) hint at a possible association between GCA and thromboembolic event (TE) risk in general. Most of these studies focus distinctly on either the arterial or the venous component of TEs, while only reporting events around the time of diagnosis. If a higher risk of VTE compared to the general population is indeed present in these patients, direct oral anticoagulants (DOACs), with or without low-dose aspirin, may now offer a safer preventative option compared to traditional warfarin regimens. Measuring the prevalence of TEs may clarify whether there is a need for thromboprophylaxis in patients with GCA. The aim of this study was to investigate the lifetime prevalence of TEs in patients with GCA along with the prevalence of risk factors associated with venous thromboembolism or stroke.

Methods: Electronic medical records (EHRs) of patients who fulfilled the following criteria were reviewed: A. Previous temporal artery biopsy (whether positive or negative) with or without non-invasive imaging of the temporal arteries and B. establishment of giant cell arteritis based on ICD-10 codes, the ACR criteria, and the clinical determination of the treating rheumatologist. Relevant data were abstracted by two trained team members out of the inpatient and outpatient (EHRs). The main outcome of interest was the earliest radiologically verified acute TE on record, including stroke, deep vein thrombosis or arterial thromboembolism, excluding prior myocardial infarction. Data regarding common thromboembolic risk factors were extracted, including concurrent COVID-19 infection, active or 5-year history of cancer and/or verified thrombophilia. In patients with stroke, relevant risk factors including atrial fibrillation, prior myocardial infarction, peripheral arterial disease, eGFR < 45 ml/min/m2, and prior revascularization procedures were identified if present.

Results: The records of 70 patients with confirmed GCA were reviewed (Mean age 75.6 years, 71% female, 9% Asian/10% African American, 44% Caucasian, 37% Race not reported). Lifetime prevalence of  TE was 14% (10/70), consisting of either stroke (9%, 6/70) or VTE (6% 4/70). Of those patients with TE, 1 patient with VTE did not have any other identifiable risk factors. The incidence rate within the 3-month period before or after the time of diagnosis was  67% for stroke events and 50% for VTE. For those 3 patients with stroke and no other identifiable risk factors, the stroke occurred within 3 months of the GCA diagnosis and two of them had evidence of anterior ischemic optic neuropathy, interestingly without complaints of headache.

Conclusion: The high lifetime prevalence of TEs in patients with GCA in this retrospective study is consistent with prior studies and further demonstrates a clustering of TEs around GCA diagnosis, especially for patients without other identifiable risk factors. This study can serve as the basis for designing future observational studies, while making the case for investigations into the efficacy of thromboprophylaxis around the time of GCA diagnosis and beyond.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/an-observational-study-of-lifetime-prevalence-of-thromboembolism-among-patients-with-giant-cell-arteritis/