Concordance between pharmacy dispensing and electronic monitoring data of direct oral anticoagulants - A secondary analysis of the MAAESTRO study.

Background: Direct oral anticoagulants are the preferred treatment for stroke patients with atrial fibrillation. Pharmacy dispensing data represent a practical method to identify suboptimal medication adherence.

Objective: This study investigates whether pharmacy dispensing data are indicative of real-life adherence behavior, using data from 130 patients in the MAAESTRO study (2018-2022) in Basel, Switzerland.

Methods: This secondary data analysis of the MAAESTRO study (Dietrich, 2024) included patients with electronic monitoring (EM) and dispensing data for 12 months. Patients with at least two refills were included in the analysis. We categorized refill series into three adherence patterns using the Delta T method (Baumgartner, 2022): all refills on time, erratic refills, end-gaps ≥10 days. EM-adherence was assessed through "taking adherence" and "missing days" (24h without intake). We analyzed: i) all dispensing data ("all refills"); ii) all data independently of the MAAESTRO phase ("all phases"); iii) the last two dispensing data ("last"), and iv) EM data from the MAAESTRO phase that match the date of the last refill ("matched"). Associations between refill patterns and adherence were examined using Spearman correlation and Fisher's exact test.

Results: Data analyzed from 50 patients (mean age 76.4 ± 9.1 years, 56.0 % male) included 252 refills with a median of 4 refills per patient. Refill patterns were: all refills on time (40.0 %), erratic refills (36.0 %), and end-gaps >10 days (24.0 %). Mean taking adherence was 89.3 ± 13.7 %. EM data revealed missing days in 82.0 % of patients, with 61.0 % having irregular refill patterns. Matched taking adherence was moderately associated with Delta T over all refills (p = 0.034) and the last refill (p = 0.013).

Conclusions: Dispensing data processed with the Delta T method correlate moderately with EM data. The Delta T value for the last two refills shows promise for estimating irregular adherence, suggesting potential for targeted interventions in pharmacy practice.