Analysis of musculoskeletal ultrasound findings and cytokines/growth factors in glucocorticoid-resistant polymyalgia rheumatica

We sought to clarify the musculoskeletal ultrasound (MSUS) findings and serum concentrations of cytokines/growth factors in glucocorticoid-resistant polymyalgia rheumatica (GC-R PMR). Patients with PMR admitted to Nagasaki University Hospital (n = 41) were enrolled. MSUS of both shoulder joints was performed in 36 patients. Patients’ sera were analyzed for cytokines/growth factors using multiplex assay kits. We examined the cases of 17 males and 24 females (median age 70 years). There were 27 GC-R patients and 14 non-GC-R patients. PD signals were detected in significantly more GC-R patients (65.2%) than non-GC-R patients (23.1%) (p = 0.035). The median serum level of vascular endothelial growth factor (VEGF) was significantly higher in the GC-R group at 871.4 pg/mL than the non-GC-R group (422.8 pg/mL) (p = 0.03) and significantly higher in the PD-positive versus PD-negative patients (p = 0.04). A multivariate analysis revealed that a high serum VEGF level was an independent variable contributing to GC resistance (p = 0.017, odds ratio: 10.34). These results suggest that a high serum VEGF level is a biomarker of GC resistance in PMR, which might be explained by PD-positive neovascularization in inflamed joints of PMR.