Which Medications Increase Microscopic Colitis Risk?

TOPLINE:

Earlier reports blamed several medications including nonsteroidal anti-inflammatory drugs (NSAIDs), proton pump inhibitors (PPIs), selective serotonin reuptake inhibitors (SSRIs), statins, and antihypertensive agents for triggering microscopic colitis. However, a Swedish study of adults aged 65 years or older found that most of these drugs didn’t increase the risk.

METHODOLOGY:

• Although medications are viewed as the main modifiable risk factors for microscopic colitis, research has been limited by nonpopulation-based samples, small and selective cohorts, and study designs vulnerable to immortal time, surveillance, and other biases.
• Researchers analyzed prescription records, hospitalizations, medical diagnoses, and gut biopsy findings of more than 2.8 million Swedish individuals aged 65 years or older to determine whether any of the previously implicated medications increased the risk for microscopic colitis.
• Target trials — one for each medication — were emulated by including only those without a history of inflammatory bowel disease or microscopic colitis, at least one healthcare encounter in the previous year, no use of a drug from the same class in the prior 180 days, and no known contraindications; the effect of initiating each medication with either not starting it or selecting an alternative therapy was compared.
• The primary outcome was biopsy-verified microscopic colitis, with researchers estimating 12- and 24-month cumulative incidences for the risk for microscopic colitis.

TAKEAWAY:

• Both 12- and 24-month cumulative incidences for the risk for microscopic colitis were < 0.5% under all treatment strategies.
• Estimated risk differences at 12 months and 24 months were close to null for the initiation of antihypertensive medications vs calcium channel blockers, initiation of NSAIDs vs noninitiation, initiation of PPIs vs noninitiation, and initiation of statins vs noninitiation.
• However, the initiation of SSRIs vs mirtazapine showed an estimated 12-month risk difference of 0.04% (95% CI, 0.03-0.05); similar results were observed for the estimated 24-month risk difference.
• The use of NSAIDs, PPIs, and SSRIs was tied to more colonoscopy exams with normal biopsy results, suggesting that the apparent rise in microscopic colitis after starting an SSRI may have reflected unmeasured bias from ongoing differences in medical care.

IN PRACTICE:

“Our study demonstrated that, contrary to the previous belief, it’s unlikely that medications are the primary triggers for microscopic colitis,” the lead author commented in a press release. “Clinicians should carefully balance the intended benefits of these medication classes against the very low likelihood of a causal relationship with MC [microscopic colitis],” the authors concluded.

SOURCE:

This study was led by Hamed Khalili, MD, MPH, Gastroenterology Unit, Department of Medicine, Massachusetts General Hospital in Boston. It was published online in the Annals of Internal Medicine.

LIMITATIONS:

The Swedish registries do not capture primary care visits, so any symptoms or diagnoses recorded there that might have prompted a colonoscopy went unmeasured. Incomplete colonoscopy records may have obscured why participants actually underwent the procedure. Furthermore, the absence of data on smoking status, body weight, laboratory results, and contraindications could have biased the findings.

DISCLOSURES:

This study was funded in part by the National Institutes of Health, the Swedish Research Council, and the Eric and Wendy Schmidt Center at the Broad Institute of MIT and Harvard. Some authors declared receiving consulting fees, serving on advisory boards, receiving financial support, and other ties with certain pharmaceutical companies.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.