Abstract 9: Consistency of Laboratory Monitoring during Initiation of Mineralocorticoid Receptor Antagonists in Heart Failure

Abstract

Introduction: The ACC/AHA heart failure guidelines recommend routine monitoring of serum potassium and renal function of patients treated with mineralocorticoid receptor antagonists (MRAs). However, compliance with these safety recommendations in routine clinical practice is unknown. Methods: We analyzed a cohort of Medicare beneficiaries in 10 states with prevalent heart failure as of July 1, 2011 and incident MRA use between May 1, 2011 and September 30, 2011. Medicare claims data were linked to laboratory results data from a large vendor. Outcomes included guideline recommended testing of serum creatinine and potassium prior to MRA initiation as well as follow-up testing in the early (day 1-10) and extended (day 11-90) post-initiation periods. Additional outcomes included abnormal laboratory results and adverse events proximate to MRA initiation. Results: We identified 10,443 Medicare beneficiaries with heart failure started on an MRA with 19.7% (2,056 of 10,443) initiated during a hospitalization. The table displays the frequency of laboratory testing before and after inpatient or outpatient MRA initiation. While overall 91.6% (9,564 of 10,443) of patients received appropriate pre-initiation testing, only 13.3% (1,384 of 10,443) received appropriate early post-initiation testing and 29.9% (3,122 of 10,443) received appropriate extended post-initiation testing. Among those patients initiated on an MRA during a hospitalization, 25.2% (518 of 2,056) had appropriate testing across all time periods. Chronic kidney disease was associated with increased likelihood of appropriate laboratory testing (RR 1.83, 95% CI: 1.58, 2.13), as was concomitant diuretic use (RR 1.78, 95% CI: 1.44, 2.21). In the early follow-up period, 1.8% (184 of 10,443) of overall patients started on a MRA had hyperkalemia or acute renal insufficiency requiring hospitalization or emergency department visit, and 8.7% (910 of 10,443) experienced these adverse events within the 90-day follow-up period. Conclusions: Rates of guideline recommended laboratory monitoring of creatinine and potassium after MRA initiation were low, which represents an area for quality improvement to ensure MRAs can safely and effectively be used in care of heart failure patients.