Use of Renally Inappropriate Medications in Older Veterans: A National Study

ObjectivesTo determine how many ambulatory older adults with chronic kidney disease receive medications that are contraindicated or dosed excessively given their level of renal function. DesignCross-sectional retrospective study. SettingU.S. Department of Veterans Affairs (VA) clinics. ParticipantsIndividuals aged 65 and older with a creatinine clearance (CrCl) of 15 to 49 mL/min (N = 83,850; mean age 80; 96% male). MeasurementsForty medications that require dose adjustment or are contraindicated in people with impaired renal function were examined. Medication use and CrCl (calculated using the Cockroft-Gault equation) were assessed using VA pharmacy, laboratory, and other data sources as of October 2007. ResultsThirteen percent of older veterans with a CrCl of 30 to 49 mL/min and 32% of those with a CrCl of 15 to 29 mL/min received one or more drugs that were contraindicated or prescribed at an excessive dose given the individual's level of renal function. The strongest risk factor for renally inappropriate prescribing was number of medications used; the risk of receiving renally inappropriate medications was 5.5 times as high (95% confidence interval = 5.1-5.9) in older adults taking 10 or more medications as in those taking one to three medications. Ranitidine, allopurinol, and metformin together accounted for 76% of renally misprescribed medications in individuals with a CrCl of 30 to 49 mL/min. Glyburide, ranitidine, gemfibrozil, carvedilol, and allopurinol accounted for 47% of renally misprescribed drugs for individuals with a CrCl of 15 to 29 mL/min. ConclusionInappropriate prescribing of renally cleared medications is common in ambulatory older veterans, with only a few medications accounting for most of these prescribing problems.