Retrospective analysis of 376 irradiated patients with ankylosing spondylitis and nonirradiated controls.

Controlled, prospective studies of deep X-ray therapy (DXT) in ankylosing spondylitis (AS) are lacking. We studied a self-help group of 1702 consecutive individuals with AS. Of these, most of whom were men, 376 (22%) had undergone DXT. An attempt was made to select a control for each. Because of the difference in ages at onset, 100 treatment recipients were matched with 100 controls (mean ages 44.5 years and 44.7 years, respectively). The mean Ankylosing Spondylitis Assessment Questionnaire disability score (range 0-8) was worse for the DXT group (5.5 vs 4.8 for controls: p less than 0.0001) and most components of the Arthritis Impact Measurement Scales showed a poorer outcome for those irradiated. Thus, 22% of nationwide AS sufferers had irradiation. This group could also have had more severe disease at the outset. At review, somewhat fewer of the irradiated group were taking NSAID. Although irradiation may have favorably affected the course of these patients our data do not support the use of irradiation except in exceptional cases.