Prescription of NSAIDs and proton pump inhibitors are associated with increased faecal calprotectin levels in patients with functional bowel disorder: an observational study.

Background: Proton pump inhibitors (PPIs) and nonsteroidal anti-inflammatory drugs (NSAIDs) have been associated with elevated fecal calprotectin (FC) levels, but their significance in functional bowel disorders remains unclear.

Objective: This study assessed the prevalence of elevated FC levels in patients referred to gastroenterologists from primary care and examined the impact of PPI and NSAID use on FC levels.

Methods: We included 431 patients with irritable bowel syndrome (IBS) or unspecified functional bowel disorders, all having at least one FC test prior to referral. Prescription data for PPIs and NSAIDs within one year of the FC test were recorded.

Results: Nineteen percent of patients had PPI prescriptions and 8% had NSAID prescriptions within 90 days of the FC test. These patients showed significantly higher FC levels than those without such prescriptions (PPIs: 66 vs. 23 μg/g, p < 0.001; NSAIDs: 57 vs. 25 μg/g, p < 0.001). A negative correlation was observed between time since PPI prescription and FC levels (rs = -0.270; p = 0.002). FC levels did not differ significantly across functional bowel disorder subtypes. A FC level >50 μg/g was associated with a higher likelihood of referral for colonoscopy (40% vs. 19%, p < 0.001).

Conclusion: PPI and NSAID use may lead to elevated FC levels, potentially causing unnecessary gastrointestinal investigations. The use of these medications should be considered when interpreting FC test results.