Clinical Features of Undifferentiated Spondyloarthropathy: Comparison with Ankylosing Spondylitis

Lee, Hye Soon; Kim, Chan; Park, Hyo Sook; Lim, Mi Kyoung; Kim, Hong Ja; Choi, Seung Won; Yoo, Bin; Moon, Hee Bom

Abstract

OBJECTIVES
To investigate the clinical features of undifferentiated spondyloarthropathy among the HLA-B27 positive arthralgic patients and to compare with those of ankylosing spondylitis.
METHODS
Two hundred and three HLA-B27 positive subjects among patients with arthralgia in various joints were classified according to the standard diagnostic criteria. The onset age, disease duration, numbers of involved joint, X-ray and bone scan findings were compared between patients with undifferentiated spondyloarthropathy(uSpA) and ankylosing spondylitis(AS).
RESULTS
1) The patients diseases were classified as ankylosing spondylitis(46%), undifferentiated spondyloarthropathy(29%), juvenile spondyloarthropathy(4%), reactive arthritis(3%), psoriatic spondyloarthropathy(1%) and unclassified(17%). 2) In undifferentiated spondyloarthropathy, the durations of the symptoms were shorter than ankylosing spondylitis and the male predominance is less prominent(5: 1 as compared to 17:1 in ankylosing spondylitis). 3) The numbers of involved peripheral joints and the frequency of peripheral joint inflammation were more frequent in undifferentiated spondyloarthropathy while the spinal joint symptoms including sacroiliac joint and the radiological severity grade of sacroiliitis were higher in ankylosing spondylitis. 4) There were no significant differences in bone scan uptake and ESR between undifferentiated spondyloarthropathy and ankylosing spondylitis.
CONCLUSION
The prevalence of undifferentiated spondyloarthropathy was notable high in HLA-B27 posicive arthralgic patients when a new classification criteria was applied, Attention should be paid on the diagnosis and progression of this elusive and challenging clinical entity.