Objective: To study prospectively the clinical evolution of different forms of spondyloarthropathy (SpA) (excluding inflammatory bowel disease, IBD): reactive arthritis, undifferentiated SpA, and ankylosing spondylitis (AS).

Methods: Ileocolonoscopy was performed on 217 patients with SpA (149 men, 68 women). They also underwent clinical, laboratory, and radiological examinations. Two to 9 years later, 123 patients (84 men, 39 women) who had been regularly monitored were reviewed and given the same examinations. For the remaining 94 patients clinical data were obtained by telephone.

Results: At the time of clinical review, 53 (43%) of the regularly monitored patients were in clinical remission. The remission rate was higher in patients with non-ankylosing spondylitis SpA (non-As-SpA) than in patients with AS (19%). Fourteen patients with non-AS-SpA had developed AS; 4 of them also had IBD. IBD was also found in 4 patients with AS and in 3 patients from the telephone group. The prevalence of HLA-B27 was significantly higher in all SpA subgroups, while HLA-BW62 was elevated in the undifferentiated SpA. At review, HLA-B27 was significantly more prevalent in patients with persistent locomotor inflammation compared to patients in clinical remission, while HLA-BW62 was predominant in the latter group.

Conclusion: Patients with SpA, especially those with non-AS-SpA, have a good longterm prognosis. However, patients with non-AS-SpA may develop AS. Six percent of the patients with SpA in whom manifestations of IBD are absent will develop this disease. This confirms the hypothesis that some of these patients with SpA initially have a form of subclinical Crohn's disease, of which locomotor inflammation is the only clinical expression. HLA-B27 positivity predisposes to a more severe course of locomotor inflammation, while HLA-BW62 has a protective effect but is associated with gut inflammation.