The natural history of Reiter's disease--21 years of observations.

Seventeen patients with Reiter's disease who were included in an earlier prospective study, were reviewed 21 years after their initial episode. Two patients had active synovitis and this correlated with the duration of the initial episode, the extent of the initial synovitis and the peak ESR. In contrast the risk of developing ankylosing spondylitis, present in five patients, was unrelated to the duration of the initial episode or the extent of the initial peripheral synovitis but was greatest in those with a higher peak ESR. A comparison of radiological features at the onset and later showed that five patients had developed bilateral sacroiliac joint fusion although two of these had some sclerosis around the sacroiliac joints at the onset. Eight patients had multifocal marginal syndesmophytes which, in four, occurred without sacroiliac changes. Plantar spur formation and hip and shoulder disease were associated with spondylitis while destructive small joint changes were a feature of Reiter's disease itself. Ten patients were HLA B27 positive. The clinical features at onset were unrelated to the B27 type. Sacroiliitis, osteitis pubis, pelvic whiskering and vertebral squaring were only present in B27 positive patients but syndesmophyte formation was unrelated to B27 type.