Risk of upper gastrointestinal bleeding with low-dose acetylsalicylic acid alone and in combination with clopidogrel and other medications.

BACKGROUND This study evaluated the risk of upper gastrointestinal bleeding (UGIB) associated with use of low-dose acetylsalicylic acid (ASA) alone and in combination with other gastrotoxic medications. METHODS AND RESULTS The Health Improvement Network UK primary care database was used to identify individuals 40 to 84 years of age with a UGIB diagnosis in 2000 to 2007 (n = 2049). An age-, sex-, and calendar year-matched control group (n = 20,000) was identified from the same source population. The relative risk (RR) of UGIB associated with use of low-dose ASA (75 to 300 mg/d), clopidogrel, and other commonly coadministered medications was estimated by multivariate logistic regression. The risk of UGIB was increased in current users of low-dose ASA (RR, 1.80; 95% confidence interval [CI], 1.59 to 2.03) or clopidogrel (RR, 1.67; 95% CI, 1.24 to 2.24) compared with nonusers. Compared with low-dose ASA monotherapy, the risk of UGIB was significantly increased when low-dose ASA was coadministered with clopidogrel (RR, 2.08; 95% CI, 1.34 to 3.21), oral anticoagulants (RR, 2.00; 95% CI, 1.15 to 3.45), low-/medium-dose nonsteroidal antiinflammatory drugs (RR, 2.63; 95% CI, 1.93 to 3.60), high-dose nonsteroidal antiinflammatory drugs (RR, 2.66; 95% CI, 1.88 to 3.76), or high-dose oral corticosteroids (RR, 4.43; 95% CI, 2.10 to 9.34); this was not apparent with coadministration of statins (RR, 0.99; 95% CI, 0.81 to 1.21) or low-dose oral corticosteroids (RR, 1.01; 95% CI, 0.58 to 1.77). CONCLUSIONS Use of low-dose ASA is associated with an almost 2-fold increase in the risk of UGIB compared with nonuse. This risk is increased further in individuals taking low-dose ASA along with clopidogrel, oral anticoagulants, nonsteroidal antiinflammatory drugs, or high-dose oral corticosteroids.