Development of Giant Cell Arteritis after Treating Polymyalgia or Peripheral Arthritis: A Retrospective Case-control Study.

Objective: We investigated the development of giant cell arteritis (GCA) in patients with prior diagnoses of isolated polymyalgia rheumatica and/or peripheral arthritis (PMR/PA), and the potentially relevant characteristics of both illnesses in such patients.

Methods: We retrospectively compared the features of 67 patients at the onset of PMR/PA, and their outcomes, to those of a random group of 65 patients with PMR/PA who did not develop late GCA. We also compared the features and outcomes of patients with late GCA to those of a random sample of patients with more usual GCA (65 with concurrent PMR/PA and 65 without).

Results: Patients with late GCA represented 7.4% of all patients with GCA included in a large hospital-based inception cohort. PMR/PA preceded overt GCA by 27 months on average. Permanent visual loss developed in 10 patients, including 8 of 48 (17%) patients featuring cranial arteritis. A questionable female predominance was the only distinguishing feature of PMR/PA evolving into GCA; late GCA more often featured subclinical aortitis (OR 6.42, 95% CI 2.39-17.23; p < 0.001), headache (OR 0.44, 95% CI 0.19-1.03; p = 0.06), and fever (OR 0.29, 95% CI 0.13-0.64; p = 0.002) less often compared to the more usual form of GCA. Patients with either form of GCA experienced similar outcomes.

Conclusion: A cranial arteritis pattern of late GCA is associated with a significant risk for ischemic blindness. However, compared to the usual form of GCA, late GCA is often less typical, with a higher frequency of silent aortitis. Patients with relapsing/refractory PMR may not be at increased risk for late GCA.