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.