Tafamidis medication adherence and persistence in patients with transthyretin amyloid cardiomyopathy in Japan

Abstract

AbstractAimsThis study aimed to describe baseline characteristics and adherence among patients with transthyretin amyloid cardiomyopathy (ATTR‐CM) treated with tafamidis (VYNDAQEL®) in Japan using the Japanese Medical Data Vision (MDV) database.Methods and resultsThis study was a non‐interventional, retrospective cohort study of adult (≥18 years old) patients in the Japanese MDV claims database diagnosed with ATTR‐CM and with at least two tafamidis prescriptions of dose strength 4 × 20 mg/day between 1 March 2019 and 31 August 2021. The date of the first prescription was defined as the index date, with follow‐up time defined as the time between the first and last prescription plus the days' supply from the last refill. Baseline characteristics were assessed during a 12 month pre‐index period. Adherence was measured using two metrics: (i) the modified medication possession ratio (mMPR), calculated by taking the sum of days supplied for all fills within the follow‐up period, divided by the number of days of follow‐up, and reported as a percentage, with patients classified as adherent with an mMPR of ≥80%, and (ii) the proportion of days covered (PDC), calculated by taking the total number of days' supply dispensed during the follow‐up period divided by the number of days of follow‐up, adjusting for any days' supply overlap. A total of 210 patients were identified; the mean (standard deviation) age of the cohort was 77 (5.9) years, and the majority (89%) were male. The most common baseline cardiovascular comorbidities were heart failure (85%), ischaemic heart disease (66%), hypertensive diseases (49%), and diabetes (35%); 75% of patients received heart failure medications in the 12 months prior to index, with the most common being beta‐blockers (49%), diuretics (48%), angiotensin receptor blockers (30%), angiotensin‐converting enzyme inhibitors (22%), and sodium–glucose cotransporter‐2 inhibitors (8.1%). Over an average 14 month follow‐up, mean mMPR was 96% with a median of 100% [inter‐quartile range (IQR): 97–101%]; 93% of patients were adherent (defined as an mMPR ≥ 80%). In the same follow‐up period, mean PDC was 93.6% with a median of 99% (IQR: 93–100%). Persistence was high with 78% of patients having a 0 day gap between prescription refills.ConclusionsThis study found high adherence rates to tafamidis in this real‐world Japanese patient population. Adherence rates in this study were similar to those reported by the tafamidis clinical trial and a previously published US commercial claims adherence analysis. Further studies should be conducted to assess the impact of real‐world adherence on real‐world outcomes.