Appropriateness of Spironolactone Prescribing in Heart Failure Patients: A Population-Based Study

BACKGROUND: The Randomized Aldactone Evaluation Study (RALES) established the safety and benefit of spironolactone for heart failure (HF) patients with systolic dysfunction. However, recent data have raised concerns regarding hyperkalemia secondary to spironolactone use and suggest it occurs more commonly in routine practice. METHODS AND RESULTS: We explored factors potentially associated with hyperkalemia from spironolactone therapy in a population-based cohort of 9165 HF patients hospitalized in Ontario, Canada, between 1999 and 2001. Compared with patients enrolled in RALES, community-based patients were older (mean age 75 years versus 65 years, P < .001) and were more likely to be female (50% versus 27%, P < .001). Of the 1502 patients that were prescribed spironolactone at discharge, 18% had elevated serum potassium levels (>5 mmol/L) during hospitalization and 23% were discharged on concurrent potassium supplements. Although only 8% of patients had serum creatinine >2.5 mg/dL, many patients had stage III (53.1%), stage IV (12.8%), or stage V (3.9%) chronic renal insufficiency according to glomerular filtration rate. CONCLUSION: Spironolactone was often prescribed to inappropriate HF candidates because of the presence of relative or absolute contraindications. These findings highlight the need for more careful patient selection when prescribing spironolactone to minimize potential life-threatening hyperkalemia.