Patiromer and maintenance of RAASi therapy in hyperkalemic medicare patients

Background: Renin angiotensin aldosterone system inhibitor (RAASi) therapy is part of the cornerstone of therapy for patients (pts) with cardiovascular disease including hypertension, CHF, and/or CAD, but use is often limited by the development of hyperkalemia. Patiromer (PAT) is a sodium (Na)-free non-absorbed potassium (K+) binder approved for hyperkalemia (HK) treatment. Patiromer has been shown to reduce recurrent HK and allow pts to maintain RAASi. Aims: This retrospective cohort study evaluated RAASi utilization among Medicare Advantage pts with HK. Methods: RAASi utilization was evaluated from a large, de-identified national health insurance claims database, Optum Clinformatics Datamart, from Janaury 1, 2016 to December 31, 2017. Three HK cohorts were identified: (1) patiromer (PAT cohort) or (2) sodium polystyrene sulfonate (SPS cohort), or (3) HK diagnosis code without K+-binder prescription (NoKb cohort). Pts were included who had a pre-index serum K+ ≥5.0 mEq/L and were continuously exposed to RAASi for ≥6 months pre-index (i.e. index date is date of first K + binder dispensing or HK diagnosis). Exposure during follow-up was classified as intent to treat (ITT) and continuous exposure (CE). ITT follow-up began on the index date and ended at the first censoring event (i.e. plan disenrollment, death, December 31, 2017) or 6 months post-index while CE also included censoring for discontinuation or switching of binder therapy (i.e. PAT or SPS). RAASi continuation and down-titration (the latter assessed for lisinopril, losartan, and valsartan) were assessed at 6 months post-index. Results: The study population included: 214 PAT pts, 2371 SPS pts, and 8531 NoKb pts. Overall, the mean age was 75 years and 50% were male. Pt comorbidities (all cohorts): CKD (48%), ESRD (1%), CHF (23%), and DM (54%). At 6 months post-index, 102 (ITT)/36 (CE) PAT pts, 1,627 (ITT)/35 (CE) SPS pts, 5,543 (ITT)/5,127 (CE) NoKb pts were evaluated. RAASi continuation rates for CE were 78%, 57%, and 57% and for ITT were 63%, 52%, and 56% in the PAT, SPS, and NoKb cohorts, respectively. Down-titration rates for the CE/ITT groups were 13/9%, 6/7%, and 7/8% in the PAT, SPS, and NoKb cohorts, respectively. Conclusions: At 6 months post-index, among continuously exposed patiromer pts, a high RAASi continuation of ∼80% was observed. RAASi continuation for pts in the SPS and NoKb cohorts was <60%. Down-titration rates of RAASi in all three cohorts were low (∼10%). Further study is warranted to fully elucidate these findings.