The relation of polymyalgia rheumatica to rheumatoid arthritis.

Sixty-four patients with the onset of rheumatoid arthritis (RA) after age 60 were followed for at least three years (mean 6.3 years); 33 patients had rheumatoid factor and 31 did not. Twenty-five of the 31 seronegative patients had an excellent response to low dose prednisone and did not require any additional medication. Six of these patients also had an episode diagnosed as polymyalgia rheumatica (PMR). These findings suggest that the synovitis currently diagnosed as seronegative RA in many older patients may not be the same disease as seropositive RA, but may be more closely related to or identical with PMR.