Infection and work stress are potential triggers of ankylosing spondylitis.

The objective of the study was to investigate potential triggering events for the onset of ankylosing spondylitis (AS). A large retrospective population survey of 1,080 AS patients was carried out by multi-faceted questionnaire. A nested case-control study compared the cohort to 102 patients with lumbar disc prolapse. Participants with AS had a mean age of 49.8 years, mean age of disease onset was 25.2 years and 63% of the cohort were male. Seventy-nine per cent knew they were human leucocyte antigen (HLA)-B27-positive, and a further 12.5% were unaware of their HLA-B27 status. Infections were relatively common in the 3 months leading to the first symptoms, 4.6% reporting gastrointestinal infection, 2.5% reporting urinary tract infection and 2.6% respiratory infection. Five per cent reported heavy physical activity in the 3 months prior to the onset of symptoms, 4.2% emotional stressors and 3.1% work stressors. Injury and surgery were less commonly reported (1.7 and 0.7%, respectively). Pregnancy was reported by 7.4% of the female participants. When the 12 months leading up to the first symptoms was compared to the 12 months previous to that, work stressors (OR 1.5), and pregnancy (OR 2.5) infection (OR 1.5 to 1.8) were significantly more common closer to disease onset. Infection and work stressors are potential triggers for the onset of AS; however, low rates suggest they are only a small part of the environmental milieu that combines with a genetic predisposition to cause the development of this chronic inflammatory disease.