Abstract
BackgroundPatients with ankylosing spondylitis (AS) are at increased risk of developing inflammatory bowel disease (IBD). We aimed to determine the variation in fecal calprotectin in AS over 5 years in relation to disease activity and medication and also to study the incidence of and predictors for development of IBD.MethodsFecal calprotectin was assessed at baseline (n = 204) and at 5-year follow-up (n = 164). The patients answered questionnaires and underwent clinical evaluations. At baseline and at 5-year follow-up, ileocolonoscopy was performed in patients with fecal calprotectin ≥500 mg/kg and ≥200 mg/kg, respectively. The medical records were checked for diagnoses of IBD during the follow-up period.ResultsFecal calprotectin >50 mg/kg was found in two-thirds of the patients at both study visits. In 80% of the patients, fecal calprotectin changed by <200 mg/kg between the two measuring points. Baseline fecal calprotectin was positively correlated with Ankylosing Spondylitis Disease Activity Score based on C-reactive protein, Bath Ankylosing Spondylitis Disease Activity Index, Bath Ankylosing Spondylitis Functional Index, C-reactive protein, erythrocyte sedimentation rate, and fecal calprotectin at 5-year follow-up. The use of nonsteroidal anti-inflammatory drugs (NSAIDs) was associated with higher fecal calprotectin, and 3-week cessation of NSAIDs resulted in a drop of a median 116 mg/kg in fecal calprotectin. The use of tumor necrosis factor (TNF) blockers was associated with lower fecal calprotectin at both visits, but the users of TNF receptor fusion proteins had significantly higher fecal calprotectin than users of anti-TNF antibodies at 5-year follow-up. The 5-year incidence of Crohn’s disease (CD) was 1.5% and was predicted by high fecal calprotectin.ConclusionsFecal calprotectin was elevated in a majority of the patients and was associated with disease activity and medication at both visits. CD developed in 1.5% of the patients with AS, and a high fecal calprotectin was the main predictor thereof. The results support a link between inflammation in the gut and the musculoskeletal system in AS. We propose that fecal calprotectin may be a potential biomarker to identify patients with AS at risk of developing IBD.Trial registrationClinicalTrials.gov identifier: NCT00858819. Registered 9 March 2009. Last updated 28 May 2015.
Highlights
Patients with ankylosing spondylitis (AS) are at increased risk of developing inflammatory bowel disease (IBD)
Fecal calprotectin was elevated in two-thirds of the patients with AS and was positively associated with parameters reflecting higher disease activity and poorer physical function at both study visits
Use of Nonsteroidal anti-inflammatory drug (NSAID) and tumor necrosis factor (TNF) receptor fusions proteins was associated with higher levels of fecal calprotectin, whereas use of anti-TNF antibodies was associated with lower levels of fecal calprotectin
Summary
Patients with ankylosing spondylitis (AS) are at increased risk of developing inflammatory bowel disease (IBD). Several risk genes are shared between the spondylarthritides and inflammatory bowel disease (IBD), and the diseases can show coinheritance [1,2,3,4]. Studies have revealed the presence of endoscopic and histologic gut inflammation in 40–60% of patients with AS and in 46% of patients with early spondylarthritis (SpA) [10,11,12,13]. The inflammation has been divided into an acute form and a chronic form, the latter resembling CD and conferring an increased risk for subsequent development of IBD [14,15,16]. 5–10% of patients with SpA eventually develop IBD, with CD being more common than UC [17, 18]. There is a lack of knowledge about what predicts the development of IBD in AS, and clinical studies on the subject are rare [19]
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