Drugs that inhibit gastric acid secretion may alter the course of inflammatory bowel disease

Recent data suggest that acid suppressive medications may alter factors central to the pathophysiology of inflammatory bowel diseases (IBD), whether through shifts in the intestinal microbiome due to acid suppression or effects on immune function.

To assess the relationship between the use of proton pump inhibitors (PPIs) or histamine2-receptor antagonists (H2Ra) and incidence of 'flares' (hospitalisation/surgery and change in medication).

We conducted a new user cohort study including individuals diagnosed with IBD in British Columbia using linked healthcare utilisation databases (available from July 1996 through April 2006). Propensity-score matched incidence rates during a 6-month follow-up period and rate ratios (RR) and 95% CI were calculated.

Among 16 151 IBD patients, 1307 Crohn's disease (CD) and 996 ulcerative colitis (UC) patients experienced a new use of PPIs, whereas 741 CD and 738 UC used H2Ra. All IBD subgroups were matched separately to an equal number of unexposed IBD patients. H2Ra use in CD doubled the risk of hospitalisation/surgery (RR = 1.94; 95%CI 1.24-3.10) and numerically less so in UC patients (RR = 1.11) with widely overlapping CIs (0.61-2.03). Proton pump inhibitors use was associated with medication change in UC (RR = 1.39; 95%CI 1.20-1.62), but without meaningfully, increased risk of hospitalisation/surgery for UC or CD patients. Extending follow-up showed persistence, but attenuation, of all effects.

Initiation of PPIs or H2Ra may be associated with short-term changes in the course of IBD. Although confounding by indication was adjusted using propensity score matching, residual confounding may persist and findings need to be interpreted cautiously.