Diagnostic Yield of Endoscopy Is Low After Initial Diagnosis of IBS
Key findings
- This study used a Swedish pathology register to examine the risk of organic disease in 21,944 patients with newly diagnosed irritable bowel syndrome (IBS) who underwent colorectal biopsy and 9,965 who underwent upper endoscopy
- Each IBS patient was matched with up to five individuals who did not have IBS and underwent colorectal biopsy (n=81,101) or upper endoscopy with biopsy (n=42,584)
- In IBS patients the odds of inflammatory bowel disease, precancerous polyps, colorectal cancer and celiac disease were 79%, 72%, 83% and 46% lower than in controls, respectively, but the odds of microscopic colitis were 77% higher
- 9.3% of all IBS patients and 16.3% of those ≥50 years old had one of these diseases detected by colonoscopy; the diagnostic yield was higher for colorectal cancer and microscopic colitis in patients ≥50 years old
- This study supports a symptoms-based diagnostic approach to IBS that does not routinely involve colonoscopy or upper endoscopy
In the U.S., 29% of colonoscopies in patients under 50 years of age are performed to investigate symptoms of irritable bowel syndrome (IBS). This is true even though data are mixed about whether colonoscopy is likely to reveal organic disease.
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Kyle Staller, MD, MPH, director of the Gastrointestinal Motility Laboratory in the Division of Gastroenterology at Massachusetts General Hospital, and colleagues investigated this issue in a large population-based cohort of patients newly diagnosed with IBS. In the European Journal of Internal Medicine, they report a low diagnostic yield of colonoscopy for colonic disease and low ability of upper endoscopy to rule out celiac disease. However, colonoscopy was important for the diagnosis of microscopic colitis in patients ≥50 years old.
Study Methods and Results
The researchers made use of the ESPRESSO study, which collected gastrointestinal pathology reports from Sweden's 28 pathology departments between 1965 and 2017. They examined results of the first colorectal biopsy of 21,944 patients after they were diagnosed with IBS and upper endoscopy biopsy results for 9,965 patients.
Each IBS patient was matched on age, sex and county with up to five individuals in the ESPRESSO cohort who did not have IBS and underwent their first colorectal biopsy (n=81,101) or upper endoscopy with biopsy (n=42,584) in the same calendar year.
Results of the study were reported as follows:
Yield of Colonoscopy
Irritable bowel disease—Crude prevalence, 1.6% in IBS patients vs. 5.9% in controls (adjusted OR (aOR), 0.21)
Precancerous polyps—4.1% vs. 13.0% (aOR, 0.28)
- Individuals ≥50 years old—8.1% vs. 24.1% (aOR, 0.27)
Colorectal cancer—0.8% vs. 6.3% (aOR, 0.17)
- Individuals ≥50 years old—1.7% vs. 13.1% (aOR, 0.16)
Microscopic colitis—2.9% vs. 1.7% (aOR, 1.77)
- IBS patients with diarrhea predominant—3.7% vs. 1.8% of controls (aOR, 2.16)
- Individuals ≥50 years old—5.3% vs. 2.2% (aOR, 2.36)
All these diseases considered together—diagnosed in 9.3% of IBS patients
- IBS patients ≥50 years old—16.3%
- IBS patients <50 years old—5.1%
Yield of Upper Endoscopy
- Celiac disease—1.9% of IBS patients vs. 3.4% of controls (aOR, 0.54)
Implications for Practice
Patient age at the time of initial IBS diagnosis is clearly an important factor in whether endoscopy will be worthwhile. In patients ≥50 years old, colonoscopy has a higher diagnostic yield for precancerous polyps, colorectal cancer and especially microscopic colitis, but IBS is primarily diagnosed in younger adults.
Therefore, this study supports a symptoms-based diagnostic approach to IBS that does not routinely involve colonoscopy or upper endoscopy. That strategy will minimize patient risk as well as conserve health care resources.
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