Diagnostic yield of endoscopy in irritable bowel syndrome: A nationwide prevalence study 1987-2016.

INTRODUCTION: Symptoms of irritable bowel syndrome (IBS) are common reasons for endoscopic procedures. We examined the yield of colonoscopy and upper endoscopy in IBS for several organic diseases.

METHODS: Matched population-based prevalence study in Sweden. We identified 21,944 participants diagnosed with IBS from 1987 to 2016 undergoing colonoscopy with a biopsy from all of Sweden's 28 pathology departments within 6 months of diagnosis. We compared prevalence of histopathology-proven diagnoses of inflammatory bowel disease (IBD), colorectal cancer, precancerous polyps, and microscopic colitis between patients recently diagnosed with IBS and matched controls without IBS (n = 81,101) undergoing colonoscopy. We also compared prevalence of celiac disease between patients diagnosed with IBS (n = 9,965) and matched controls (n = 45,584) undergoing upper endoscopy with biopsy. IBS patients were also compared to their siblings. Conditioned logistic regression estimated adjusted odds ratios (aORs).

RESULTS: Biopsy-proven IBD was seen in 1.6% of IBS and in 5.9% of controls (aOR=0.21; 95%CI=0.19-0.24). The prevalence of precancerous polyps was 4.1% vs. 13.0% (aOR=0.28; 95%CI=0.26-0.30), colorectal cancer 0.8% vs. 6.3% (aOR=0.17; 95%CI=0.14-0.20) and celiac disease 1.9% vs. 3.4% (aOR=0.54; 95%CI=0.47-0.63). Conversely, the prevalence of microscopic colitis was 2.9% vs. 1.7% (aOR=1.77; 95%CI=1.61-1.95), with higher prevalence in older patients and patients with IBS with diarrhea. Yield of colonoscopy for precancerous polyps, colorectal cancer, and microscopic colitis increased by age. Our findings were consistent using unaffected siblings as the comparator group.

DISCUSSION: The diagnostic yield of upper endoscopy and colonoscopy for organic disease is low in patients with a first-time diagnosis of IBS, though increases with age.