Difference between the frequencies of antisecretory drug prescriptions in users of buffered vs. enteric-coated low-dose aspirin therapies.

OBJECTIVE: To provide further insights on the risks of gastrointestinal (GI) complications in individuals using low-dose aspirin (LDA), we investigated the concomitant use of LDA and antisecretory drugs. Additionally, we examined the frequency distributions of prescribing sequences for LDA and antisecretory drugs. METHODS: Data from a computerized prescription order entry system was analyzed at the National Cerebral and Cardiovascular Center of Japan. LDA use in combination with H2-receptor antagonists (H2RAs) and proton pomp inhibitors (PPIs) was examined over the period from January 2001 to December 2010. Prescription sequence symmetry analyses were used to identify LDA-induced H2RAs or PPIs users. RESULTS: In December 2010, PPIs accounted for 9.9% of the prescriptions for buffered LDA users and 16.1% of those for enteric-coated LDA users. Incident use of PPIs occurred more frequently among enteric-coated LDA users than buffered LDA users (17.6% vs. 11.0%, respectively). Prescription sequence symmetry analyses of PPI use revealed significant associations with enteric-coated LDA use, resulting in adjusted sequence ratios of 1.82 (95%CI, 1.11 - 3.03) and 1.87 (95% CI, 1.26 - 2.83) at intervals of 182 and 365 days, respectively. Enteric-coated LDA users tended to initiate PPI therapy on the same date more frequently than buffered LDA users (35.1% vs. 10.8%, respectively). CONCLUSIONS: Our findings do not support the notion that entericcoated LDA products confer a lower risk for GI complications than buffered formulations, but may conversely imply that the risk of GI complications associated with buffered LDA is lower than that of enteric-coated LDA.