Clinical and laboratory features at onset of polymyalgia rheumatica (PMR) and elderly onset of rheumatoid arthritis in PMR-like presentation: A comparison of two groups of patients

The differential diagnosis between polymyalgia rheumatica (PMR) and elderly onset rheumatoid arthritis (EORA) in PMR-like presentation may represent several problems at the beginning of the disease, since the patterns of these pathologies may show largely overlapping areas. In this study we examined clinical and laboratory features of 21 patients with PMR and 22 patients with EORA PMR-like presentation, to identify eventual differences between the 2 diseases. EORA PMR-like presentation occurred more frequently in males (14 men and 8 women) than PMR (6 men and 15 women) (p = 0.046). In EORA PMR-like presentation we observed higher levels of gamma-globulins (p = 0,003), immunoglobulins IgG (p = 0.004), IgA (p = 0.002) and IgM (p = 0.014) than in PMR. Fever (p = 0.022), asthenia (p = 0.007) and the contemporary involvement of the shoulder and pelvic girdle (p = 0.0054) were more frequent in PMR patients than EORA PMR-like presentation patients. Moreover, the involvement of the shoulder girdle only (p = 0.0054) and arthritis of the peripheral joints (p = 0.045) were more frequent in EORA PMR-like presentation than in PMR patients. The results of this preliminary study revealed different clinical and laboratory features that may offer additional help in differential diagnosis at onset of the 2 diseases.