A Population-Based Study

Methods: We conducted a population-based, nested casecontrol study of a cohort of elderly patients 66 years or older who were residents of Ontario, Canada, and who were receiving continuous therapy with either an ACEI or an ARB. Case patients were those with a hyperkalemiaassociated hospitalization within 14 days of receiving a prescription for trimethoprim-sulfamethoxazole, amoxicillin, ciprofloxacin, norfloxacin, or nitrofurantoin. For each case, we identified up to 4 control patients from the same cohort matched for age, sex, and presence or absence of chronic renal disease and diabetes. Odds ratios were determined for the association between hyperkalemiaassociated hospitalization and previous antibiotic use.