Predicting Crohn’s Disease in Those with Ankylosing Spondylitis

By Spondylitis Association of America

Friday, February 24, 2017

A recent study found a strong association between increased levels of an inflammatory marker in the gut and the subsequent development of Crohn’s disease in those with existing ankylosing spondylitis.

Patients participating in the study were asked to provide stool and blood samples, as well as to complete a questionnaire at the beginning of the study, (to establish their baseline scores) and once again five years later at the follow up visit. Of the 204 patients with ankylosing spondylitis initially enrolled in the study, 164 (80%) completed the study by returning for the follow up examination.

Researchers found that an elevated level of gut inflammation at the start of the study – as evidenced by increased levels of a protein called calprotectin in the stool – was a strong predictor of the development of Crohn’s disease within five years.

“Baseline level of fecal calprotectin among AS patients who had been diagnosed with Crohn's disease 5 years later was higher, at 570 mg/kg, compared with 85 mg/kg (P=0.014) among those who did not develop the inflammatory bowel disease (IBD)…”

*Crohn’s is a form of inflammatory bowel disease (IBD)

The researchers concluded that, “fecal calprotectin may be a potential biomarker to identify patients with AS at risk of developing IBD.” However, whether medical intervention in those susceptible to IBD is appropriate, or may be effective remains to be seen.

The authors also note, “Our results indicate that gut inflammation in AS is associated with higher disease activity in rheumatic disease…the longitudinal results of our study support the hypothesis that inflammation in the gut and the musculoskeletal system may be linked.”

There has been little past research into risk assessment and possible predicting factors for the development of IBD in those with ankylosing spondylitis. This is despite the fact that approximately 10% of ankylosing spondylitis patients develop a form of IBD (most commonly Crohn’s disease) within 20 years of an AS diagnosis, and that up to 60% of the population with AS who have no gastrointestinal symptoms have some level of gut inflammation.

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