Back to Journals » Drug, Healthcare and Patient Safety » Volume 10

Development and validation of a questionnaire to self-assess patient knowledge of direct oral anticoagulants (KODOA-test)

Authors Metaxas C, Albert V, Stahl M, Hersberger KE, Arnet I

Received 30 September 2017

Accepted for publication 9 March 2018

Published 20 July 2018 Volume 2018:10 Pages 69—77


Checked for plagiarism Yes

Review by Single-blind

Peer reviewer comments 2

Editor who approved publication: Dr Rajender R Aparasu

Corina Metaxas,1 Valerie Albert,1 Matthias Stahl,2 Kurt E Hersberger,1 Isabelle Arnet1

1Department of Pharmaceutical Sciences, Pharmaceutical Care Research Group, University of Basel, Basel, Switzerland; 2Department of Internal Medicine, Kantonsspital Basel-Land, Bruderholz, Switzerland

Objective: Few studies have examined associations between patient knowledge of direct oral anticoagulants (DOAC) and clinical outcomes, mostly because of the lack of validated questionnaires for assessing knowledge. The aim of this study was to develop and validate a questionnaire to self-assess knowledge of DOAC.
Methods: Twelve anticoagulation experts participated in the questionnaire development process to ensure content validity. The Knowledge Of Direct Oral Anticoagulants (KODOA)-test was submitted to patients on DOAC and to pharmacists to assess construct validity. Responsiveness was evaluated after educational counseling. Test–retest reliability was assessed to ensure stability over time, and Cronbach’s α was calculated for internal reliability. Index of difficulty and item discrimination (D-value) were calculated to assess the performance of single items.
Results: The KODOA-test contains 15 items with multiple-choice answers. Each correct answer scores 1 point (max. score of 15). The KODOA-test was administered to 32 patients on DOAC and 28 pharmacists. Pharmacists scored significantly higher than patients at baseline (median score 13.3 vs 10.0; p<0.001), supporting construct validity. Patient scores increased significantly after educational counseling (median score 11 [interquartile range 2] vs 14 [interquartile range 3]; p<0.001). Test–retest and Cronbach’s α were acceptable with a Pearson’s correlation of 0.8 and an α of 0.67. The index of difficulty for most items was satisfactory (0.38–0.72) and the mean D-value was 42.5%.
Conclusion: The KODOA-test is a brief, valid, and reliable knowledge self-assessment questionnaire that may be used in clinical trials to investigate associations between knowledge increase and patient-related outcomes.

Keywords: patient knowledge, direct oral anticoagulants, questionnaire development, adherence, validation

Creative Commons License This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at and incorporate the Creative Commons Attribution - Non Commercial (unported, v3.0) License. By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms.

Download Article [PDF]  View Full Text [HTML][Machine readable]