To investigate if there are differences in radiological findings in lumbosacral spine radiographs between different subgroups of patients with previous reactive arthritis.
95 patients with previous enteroarthritis (n = 53), uroarthritis (n = 37), or Reiter's syndrome, aetiology unknown (n = 5) were included in the study. Lumbosacral radiographs were taken 7 to 38 years after the initial arthritis. Three independent observers read the radiographs. Spinal changes included squaring of vertebrae, Romanus lesions, syndesmophytes, and osteophytes. Sacroiliitis was recorded according to the New York and Stoke methods. Signs of enthesitis in the iliac crest and disc space narrowing were recorded. Interobserver reliability and intraobserver reproducibility were determined.
23% of patients had grade 2-4 sacroiliitis (New York criteria) and 14% had syndesmophytes. There was more frequent sacroiliitis (32% v 13%) in uroarthritis than in enteroarthritis, and more syndesmophytes (mean 0.54 v 0.15 per patient; prevalence 24% v 6%, respectively). In other radiological features, no significant differences were present between the groups. In the material as a whole, patients with sacroiliitis of grade 2 or more had significantly less disc space narrowing both in patient comparisons (chi(2) test) and in numbers of spaces involved (Mann-Whitney test). Interobserver and intraobserver agreement, calculated using Cohen's kappa method, varied from 0.2 to 1.
Syndesmophytes and sacroiliitis are more common in patients with previous uroarthritis than in those with previous enteroarthritis, but radiological findings in lumbosacral spine radiographs are characteristically similar.