Hospitalization for gastrointestinal adverse events attributable to the use of low-dose aspirin among patients 50 years or older also using non-steroidal anti-inflammatory drugs: a retrospective cohort study

Background Use of aspirin with non-steroidal anti-inflammatory drugs increases the risk of gastrointestinal ulcers; however, it is not clear if this risk varies with the non-steroidal anti-inflammatory drug used. Aim To assess the risk of gastrointestinal hospitalizations attributable to aspirin in patients 50 years or older also using non-steroidal anti-inflammatory drugs. Methods Administrative data of patients 50 years or older who received a nonsteroidal anti-inflammatory drug or acetaminophen prescription between 1998 and 2004 were used. Results Study patients received 7 412 992 non-steroidal anti-inflammatory drug prescriptions and 5 614 044 acetaminophen prescriptions among which 23% and 32%, respectively, were dispensed to aspirin users. Time-dependent Cox regression models revealed that, compared to patients using acetaminophen ( without aspirin), the adjusted hazard ratio ( 95% CI) among non-users of aspirin were: rofecoxib 1.3 (1.2, 1.5), celecoxib 0.7 (0.6, 0.8), diclofenac 1.5 (1.2, 1.7), ibuprofen 0.9 (0.6, 1.4), naproxen 2.5 (2.1, 3.0) and piroxicam 1.5 (0.8, 2.8); among users of aspirin: rofecoxib 3.2 ( 2.8, 3.7), celecoxib 1.8 ( 1.5, 2.1), diclofenac 2.8 (2.2, 3.5), ibuprofen 1.4 ( 0.8, 2.7), naproxen 2.2 (1.6, 3.0) and piroxicam 2.0 (0.8, 5.4). The risk attributable to aspirin varied from none with naproxen to 61% (53%, 68%) with celecoxib. Conclusion The increase in gastrointestinal hospitalization attributable to aspirin differed with the non-steroidal anti-inflammatory drug used, and seemed higher with cyclo-oxygenase-2 inhibitors than with non-selective non-steroidal anti-inflammatory drugs.