Angiotensin receptor‐neprilysin inhibitor adherence and outcomes in heart failure with reduced ejection fraction

Aims Whether medication adherence to angiotensin receptor‐neprilysin inhibitor (ARNI) in real‐world practice is associated with the reduced risk of all‐cause mortality or hospitalization relative to that with traditional renin–angiotensin system (RAS) blockade remains unclear. This study investigated the influence of medication adherence of ARNI and traditional RAS blockade in heart failure with reduced ejection fraction (HFrEF). Method We conducted a nationwide longitudinal cohort study with patients with HFrEF using data from the Korean National Health Insurance Service data (2017–2021) covering the entire population. A total of 13 483 patients with HFrEF who received ARNI were matched 1:1 with 13 483 patients who received traditional RAS blockade using propensity score matching. The primary outcome was a composite of all‐cause mortality or any hospitalization within one year. Medication adherence was assessed by calculating the proportion of days covered (PDC) relative to total medication prescribed. ARNI and traditional RAS blockade adherence rates were directly compared to analyse their respective associations with the primary outcome. Results Patients in the ARNI group had a lower rate of the primary outcome than those in the traditional RAS blockade group [hazard ratio (HR) 0.78; 95% confidence interval (CI) 0.75–0.81; P