Jerry H. Gurwitz, MD
In older patients, does concomitant use of warfarin and antibiotics to treat urinary tract infection (UTI) increase risk for upper gastrointestinal (UGI) hemorrhage?
Population-based, nested case–control study using database linkage.
Cases and controls (median age 80 y, 52% men) were identified from 134 637 Ontario residents who received continuous warfarin for ≥ 180 days beginning after their 66th birthday. Cases were patients who were hospitalized with UGI hemorrhage (index date = date of hospitalization) (n = 2151). Up to 10 control patients were matched to each case based on date of birth, sex, and warfarin use on the case’s index date (n = 21 434). Exclusion criteria were hospitalization for hemorrhage during the first 180 days of warfarin therapy, discharge from hospital for any diagnosis ≤ 30 days before the index date, use of amoxicillin in combination products for Helicobacter pylori infection, or use of ≥ 1 study antibiotic (see below) ≤ 14 days before the index date.
Oral cotrimoxazole prescription ≤ 14 days before the index date, along with other oral antibiotic prescriptions to treat UTI (ciprofloxacin, amoxicillin or ampicillin, norfloxacin, and nitrofurantoin) for comparison.
Hospitalization for UGI hemorrhage.
Cases were more likely than controls to have received either cotrimoxazole or ciprofloxacin ≤ 14 days before admission for UGI hemorrhage (Table). Admission for UGI hemorrhage was not associated with use of nitrofurantoin, amoxicillin or ampicillin, or norfloxacin ≤ 14 days before admission (Table).
In older patients, concomitant use of warfarin and oral cotrimoxazole or ciprofloxacin was associated with increased risk for hospitalization with upper gastrointestinal hemorrhage.
Association between use of antibiotics ≤ 14 days before admission in patients receiving warfarin for >180 consecutive days and admission for UGI hemorrhage*
*UGI = upper gastrointestinal; other abbreviations defined in Glossary.
†Adjusted for history of UGI hemorrhage, UGI diagnostic examination, or any hemorrhage except UGI; history of cirrhosis and alcoholism; number of prescription drugs within 1 y of index date; long-term care status; other antibiotics; and other concomitant drug use.
Gurwitz JH. Concomitant use of warfarin and cotrimoxazole or ciprofloxacin increased risk for admission for upper GI hemorrhage. Ann Intern Med. ;153:JC3–13. doi: 10.7326/0003-4819-153-6-201009210-02013
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Published: Ann Intern Med. 2010;153(6):JC3-13.
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Print ISSN: 0003-4819 | Online ISSN: 1539-3704
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