Subclinical giant cell arteritis (GCA) may present as a comorbidity in more than 25% of patients with newly diagnosed polymyalgia rheumatica (PMR), according to study results published in Seminars in Arthritis and Rheumatism.
A global group of researchers conducted a systematic review and meta-analysis to assess the prevalence of GCA in patients newly diagnosed with PMR. They analyzed 2362 studies published between 1965 and 2020 on PubMed, Web of Science Core Collection, and Embase, finalizing the inclusion of 13 cohorts with a total of 566 patients into the study.
Clinicians in these 13 studies used temporal artery biopsy (n=3), ultrasonography (n=3), and positron emission tomography/computed tomography (PET/CT) scans (n=7) to screen for and diagnose subclinical GCA.
Pooled prevalence was 20% in patients with PMR whose subclinical GCA was diagnosed by biopsy (CI, 7%-46%, I2=86%), 15% by ultrasonography (CI, 3%-50%, I2=86%), and 29% by PET/CT scans (CI, 13%-53%, I2=85%). The combined pooled prevalence of subclinical GCA in patients newly diagnosed with PMR was 23% (CI, 14%-36%, I2=84%).
Inflammatory back pain, lack of lower extremity pain, female sex, body temperature over 37.0°C, weight loss, thrombocyte count, and hemoglobin levels strongly predicted development of subclinical GCA. Conversely, C-reactive protein levels, erythrocyte sedimentation rate, leukocyte count, age, neck pain, pelvic girdle pain, and duration of morning stiffness did not predict development of subclinical GCA.
Limitations of the study included recruitment of patients with PMR solely from specialist offices when primary care physicians treat most patients with PMR, as well as study heterogeneity, especially the different diagnostic measures for each study. Incomplete individual patient data weakened the study’s statistical strength and analysis only of routine laboratory biomarkers overlooked angiopoietin-2, a newly identified biomarker for large vessel vasculitis.
The study authors concluded that while most variables predicted increased likelihood of subclinical GCA development, an increase in hemoglobin level by 1 g correlated with decreased likelihood of developing subclinical GCA. They added, “This systematic review and meta-analysis indicated that subclinical GCA might affect more than one in four patients with PMR when screened by PET/CT at diagnosis…. Due to the high prevalence of subclinical GCA at PMR diagnosis, the role of routine imaging for GCA warrants discussion.”
Disclosure: Several study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Hemmig AK, Gozzoli D, Werlen L, et al. Subclinical giant cell arteritis in new onset polymyalgia rheumatica A systematic review and meta-analysis of individual patient data. Semin Arthritis Rheum. Published online April 28, 2022. doi:10.1016/j.semarthrit.2022.152017