Polymyalgia Rheumatica and Giant Cell Arteritis: A Systematic Review.

IMPORTANCE: Polymyalgia rheumatica (PMR) and giant cell arteritis (GCA) are related inflammatory disorders occurring in persons aged 50 years and older. Diagnostic and therapeutic approaches are heterogeneous in clinical practice.

OBJECTIVE: To summarize current evidence regarding optimal methods for diagnosing and treating PMR and GCA.

EVIDENCE REVIEW: MEDLINE, EMBASE, and Cochrane databases were searched from their inception dates to March 30, 2016. Screening by 2 authors resulted in 6626 abstracts, of which 50 articles met the inclusion criteria. Study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool or American College of Cardiology Foundation/American Heart Association methodology.

FINDINGS: Twenty randomized clinical trials for therapy (n = 1016 participants) and 30 imaging studies for diagnosis and/or assessing response to therapy (n = 2080 participants) were included. The diagnosis of PMR is based on clinical features such as new-onset bilateral shoulder pain, including subdeltoid bursitis, muscle or joint stiffness, and functional impairment. Headache and visual disturbances including loss of vision are characteristic of GCA. Constitutional symptoms and elevated inflammatory markers (>90%) are common in both diseases. Ultrasound imaging enables detection of bilateral subdeltoid bursitis in 69% of PMR patients. In GCA, temporal artery biopsy remains the standard for definitive diagnosis. Ultrasound and magnetic resonance imaging (MRI) of large vessels revealing inflammation-induced wall thickening support the diagnosis of GCA (specificity 78%-100% for ultrasound and 73%-97% for MRI). Glucocorticoids remain the primary treatment, but the optimal initial dose and tapering treatment regimens are unknown. According to consensus-based recommendations, initial therapy for PMR is prednisone, 12.5 to 25 mg/day or equivalent, and 40 to 60 mg/day for GCA, followed by individualized tapering regimens in both diseases. Adjunctive methotrexate may reduce cumulative glucocorticoid dosage by 20% to 44% and relapses by 36% to 54% in both PMR and GCA. Use of tocilizumab as additional treatment with prednisone showed a 2- to 4-fold increase in remission rates of GCA in a randomized clinical trial (N = 30).

CONCLUSIONS AND RELEVANCE: Diagnosis of PMR/GCA is made by clinical features and elevated inflammatory markers. In PMR, ultrasound imaging may improve diagnostic accuracy. In GCA, temporal artery biopsy may not be required in patients with typical disease features accompanied by characteristic ultrasound or MRI findings. Consensus-based recommendations suggest glucocorticoids as the most effective therapy for PMR/GCA. Methotrexate may be added to glucocorticoids in patients at risk for relapse and in those with glucocorticoid-related adverse effects or need for prolonged glucocorticoid therapy.