No Cover Image

Journal article 264 views 70 downloads

Determining Drug Exposure Based on Medication Dispensing Data: A Validation Study of Vitamin K Antagonist Treatment Episodes Against INR Records

Eva K. Kempers Orcid Logo, Chantal Visser, Jamilla Goedegebuur, Qingui Chen, Mette Søgaard, Anne Gulbech Ording, Carline van den Dries, Denise Abbel, Sarah Aldridge, Kate J. Lifford, Johanneke E. A. Portielje, Melchior C. Nierman, Annelies Boetes‐Draisma, Sjef J. C. M. van de Leur, Frederikus A. Klok, Eric C. T. Geijteman, Marieke J. H. A. Kruip, Suzanne C. Cannegieter

Pharmacoepidemiology and Drug Safety, Volume: 34, Issue: 6, Start page: e70158

Swansea University Author: Sarah Aldridge

  • pds.70158.pdf

    PDF | Version of Record

    © 2025 The Author(s). This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License (CC BY-NC).

    Download (2.07MB)

Check full text

DOI (Published version): 10.1002/pds.70158

Abstract

Background: In pharmaco‐epidemiological studies using vitamin K antagonist (VKA) exposure, constructing treatment episodes based on dispensed prescriptions is challenging, particularly due to the large variability in therapeutic dose. Objectives: To validate different methods of constructing VKA tre...

Full description

Published in: Pharmacoepidemiology and Drug Safety
ISSN: 1053-8569 1099-1557
Published: Wiley 2025
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa69540
Abstract: Background: In pharmaco‐epidemiological studies using vitamin K antagonist (VKA) exposure, constructing treatment episodes based on dispensed prescriptions is challenging, particularly due to the large variability in therapeutic dose. Objectives: To validate different methods of constructing VKA treatment episodes based on dispensed prescriptions, using VKA exposure based on international normalized ratio (INR) measurements as a reference. Methods: Data from five Dutch anticoagulation clinics were linked to VKA dispensing data from Statistics Netherlands. Three random samples of 10 000 VKA users between 2013 and 2019 were used to compare the construction of VKA treatment episodes based on dispensings, applying fixed or dynamic methods, against the reference of exposure based on INR measurements. A total of 60 different methods were validated by computing the percentage of INR measurements occurring outside dispensing‐based VKA treatment episodes, the ratio of VKA‐exposed person‐time based on dispensings vs. INR measurements, and the number of dispensing‐based episodes. Results: Depending on the method used to construct treatment episodes, 14.8%–42.2% of the INR measurements were not covered by a dispensing‐based episode. The VKA‐exposed person‐time ratio ranged between 0.73 and 1.13, and there was substantial variability in the number of dispensing‐based episodes. Fixed methods resulted in a lower percentage of INR measurements outside the dispensing‐based episodes, a VKA‐exposed person‐time ratio closer to 1.0, and a lower number of constructed episodes. Conclusion: Fixed methods performed better than dynamic methods when classifying VKA exposure based on dispensing data. Our findings may guide other researchers working with VKA dispensing data, especially when the tablets dispensed or the prescribed dose are unavailable.
Keywords: acenocoumarol, anticoagulants, epidemiologic methods, pharmacoepidemiology, phenprocoumon
College: Faculty of Medicine, Health and Life Sciences
Issue: 6
Start Page: e70158