Abstract | BACKGROUND: METHODS: This population-based, nested case-control study using health care databases in Ontario, Canada, between April 1, 1997, and March 31, 2007, identified residents 66 years or older who were continuously treated with warfarin. Cases were hospitalized with UGI tract hemorrhage. For each case, we selected up to 10 age- and sex-matched control subjects. We calculated adjusted odds ratios (aORs) for exposure to cotrimoxazole, amoxicillin trihydrate, ampicillin trihydrate, ciprofloxacin hydrochloride, nitrofurantoin, and norfloxacin within 14 days before the UGI tract hemorrhage. RESULTS: We identified 134 637 patients receiving warfarin, of whom 2151 cases were hospitalized for UGI tract hemorrhage. Cases were almost 4 times more likely than controls to have recently received cotrimoxazole (aOR, 3.84; 95% confidence interval [CI], 2.33-6.33). Treatment with ciprofloxacin was also associated with increased risk (aOR, 1.94; 95% CI, 1.28-2.95), but no significant association was observed with amoxicillin or ampicillin (1.37; 0.92-2.05), nitrofurantoin (1.40; 0.71-2.75), or norfloxacin (0.38; 0.12-1.26). Compared with amoxicillin or ampicillin, cotrimoxazole prescription was associated with an almost 3-fold risk (ratio of ORs, 2.80; 95% CI, 1.48-5.32). CONCLUSIONS:
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Authors | Hadas D Fischer, David N Juurlink, Muhammad M Mamdani, Alexander Kopp, Andreas Laupacis |
Journal | Archives of internal medicine
(Arch Intern Med)
Vol. 170
Issue 7
Pg. 617-21
(Apr 12 2010)
ISSN: 1538-3679 [Electronic] United States |
PMID | 20386005
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Anti-Infective Agents, Urinary
- Anticoagulants
- Warfarin
- Ampicillin
- Amoxicillin
- Trimethoprim, Sulfamethoxazole Drug Combination
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Topics |
- Aged
- Aged, 80 and over
- Amoxicillin
(adverse effects)
- Ampicillin
(adverse effects)
- Anti-Infective Agents, Urinary
(adverse effects)
- Anticoagulants
(adverse effects)
- Case-Control Studies
- Databases, Factual
- Drug Interactions
- Drug Therapy, Combination
- Female
- Gastrointestinal Hemorrhage
(chemically induced)
- Humans
- Male
- Multivariate Analysis
- Odds Ratio
- Ontario
- Trimethoprim, Sulfamethoxazole Drug Combination
(adverse effects)
- Urinary Tract Infections
(drug therapy)
- Warfarin
(adverse effects)
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