Outpatient Cost-effectiveness Study of Hyperkalemia Management

Abstract

Introduction Patiromer (PAT) is a sodium free, non-absorbed potassium (K+) binder approved for the treatment of hyperkalemia (HK). There is limited real-world evidence on the outpatient cost implications associated with PAT treatment of HK. Hypothesis To assess the cost-effectiveness of treating HK with PAT vs. no K+ binder in a Medicare Advantage population. Methods This retrospective, matched cohort study was conducted using Optum's de-identified Clinformatics® Data Mart Database from 1/1/16-12/31/18. Two HK cohorts were identified: PAT exposed/unexposed (NoPAT). Inclusion criteria included pre-index serum K+ ≥5.0 mEq/L, HK diagnosis (ICD-10 code) and ≥6 months insurance enrollment post-index. Propensity score matching and coarsened exact matching with baseline variables were used to identify the complete set of matching unexposed and exposed HK episodes. Follow-up began on the index date and ended at the first censoring event (insurance disenrollment, death, 12/31/18, sodium polystyrene sulfonate [SPS] or sodium zirconium cyclosilicate [SZC] initiation, PAT discontinuation [exposed only], PAT initiation [unexposed only]). A zero-inflated negative binomial regression model was performed on the outcomes. Outpatient outcomes were defined as any costs not identified as inpatient, ED or pharmacy. Outpatient cost outcomes were measured at 6 months post-index (mean US$ [CI 95%]). Results The study population included 2004 patients (1002 matched pairs), the mean age was 74 years and 60% were male. Patients had a mean of 5 comorbidities, most commonly diabetes mellitus (73%), congestive HF (35%), and end-stage renal disease (10%). At 6 months post-index, 300 (150 matched pairs) PAT and NoPAT patients remained uncensored and, of those, 299 had non-zero outpatient costs evaluated; total PAT outpatient mean cost difference (savings) was $4828 ($2205, $5833; P ≤0.004) for PAT vs. NoPAT patients. ConclusionS In a matched-cohort design of individuals with hyperkalemia covered with Medicare Advantage, patiromer usage was associated with a 35% reduction in outpatient costs over a 6-month period compared to those that were not treated with patiromer. Further study is warranted to replicate these findings in a large cohort.