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Mixed-methods approach to determine adherence, knowledge and behavioral determinants associated with medication wastage.

West, Lorna Marie; Stewart, Derek; Cordina, Maria


Lorna Marie West

Derek Stewart

Maria Cordina


Background: While literature quantifying medication wastage and assessing public's knowledge and practices about medication disposal is substantial, less attention is given to the public's knowledge and behavior pertaining to medication wastage prevention. This study aimed to determine the public's knowledge of medication wastage, any association between knowledge and adherence, and behavioral determinants potentially leading to wastage. Methods: A mixed-method explanatory sequential approach was adopted with a quantitative survey followed by qualitative semi-structured interviews. Maltese residents ≥18 years attending social/educational events were recruited in this mixed-methods study. Participants completed a structured questionnaire comprising: 1) demographics; 2) medication adherence using ‘Tool for Adherence Behaviour Screening’ dichotomized into ‘good adherence’/‘suboptimal adherence’; 3) eight knowledge statements each carrying one point (total, 0 = lowest; 8 = highest); 4) and whether they had unused medication at home. Chi-square analysis determined associations between demographics and adherence, and having unused medication. Multiple regression was performed to predict knowledge based on demographics, adherence, having regular medication and having unused medication, p ≤0.05. Questionnaire respondents expressing interest in participating in semi-structured face-to-face interviews, based on the Theoretical Domains Framework (TDF), were recruited consecutively until data saturation. Interviews were audio-recorded, transcribed and analyzed using the Framework Approach. Results: Of the 524 individuals attending 14 events, 80.5% completed the questionnaire (mean age±standard deviation (SD): 65 ± 13 years). Thirty-one percent (n = 130/422) of respondents reported having unused medication and 18.8% (58/309 taking chronic medication) classified as ‘optimal’ adherence. Mean ± SD knowledge score was 4.7 ± 1.5. Knowledge and adherence were not significantly related. Most prevalent TDF domains influencing wastage emerging from 15 interviews were knowledge, beliefs about consequences and behavioral regulation. Conclusion: Public's knowledge about medication wastage and adherence were inadequate, necessitating implementation of tailored educational interventions based on behavioral determinants recognized within this study. Identified inadequate behavior around disposal mandates inclusion of environmental/social planning issues when developing policies.


WEST, L.M., STEWART, D. and CORDINA, M. 2020. Mixed-methods approach to determine adherence, knowledge and behavioral determinants associated with medication wastage. Research in social and administrative pharmacy [online], 16(5), pages 654-662. Available from:

Journal Article Type Article
Acceptance Date Aug 1, 2019
Online Publication Date Aug 1, 2019
Publication Date May 31, 2020
Deposit Date Sep 3, 2019
Publicly Available Date Aug 2, 2020
Journal Research in Social and Administrative Pharmacy
Print ISSN 1551-7411
Electronic ISSN 1934-8150
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 16
Issue 5
Pages 654-662
Keywords Adherence; Behavioral determinants; Community; Knowledge; Theoretical domains framework; Medication wastage
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