The development of a Core Outcome Set for clinical trials targeting interventions aiming to improve adherence to appropriate polypharmacy in older people – A Delphi consensus study

Abstract Introduction Older people encounter challenges when taking polypharmacy. Different interventions have been applied to improve adherence to polypharmacy. However, there are few high-quality studies, and little consideration has been given to the outcomes selected to measure the effectiveness of interventions.1 To produce high-quality studies and accurately report adherence-related outcomes, developing a Core Outcome Set (COS) is important.2 A COS is the minimum number of outcomes that should be reported and measured in future trials in a specific health field to reduce outcomes’ inconsistencies across trials.2 Aim This study aimed to develop a COS for use in clinical trials aiming at improving adherence to appropriate polypharmacy in older patients. Methods A list of outcomes related to adherence to polypharmacy (n=13) was compiled from previous semi-structured interviews with stakeholders. The Delphi panel consisted of experts in adherence, polypharmacy and gerontology, including journal editors, academics, non-National Health Service doctors, nurses and pharmacists who were identified by searching researchers’ publication profiles using Google Scholar and Scopus. Senior editors and editor-in-chief of peer-reviewed journals were identified by searching journal information. Public members were identified by searching for contact emails of staff members in public charities/organisations representing older people’s healthcare needs (e.g. AgeUK). Additionally, identified participants received invitation emails asking them to forward the email to other participants and experts who might be interested in this study (i.e. snowball sampling). The 13 outcomes were distributed in three online Delphi questionnaires between February and April 2023 using an online SoGoSurvey® platform. All outcomes were rated according to their degree of importance using a nine-point Likert scale (1 to 3 = unimportant; 4 to 6 = important but not critical; 7 to 9 = critical). Following each round, response rates and the distribution of scores were calculated to classify outcomes into ‘consensus in’, ‘consensus out’ and ‘no consensus’. An outcome was considered very important if ≥80% of participants scored it as ‘critical’ and ≤15% scored it as ‘unimportant’. Results The Delphi panel (Round 1, n=57; Round 2, n=53; Round 3, n=50) comprised different professionals, including 38 academics, 23 pharmacists, 12 doctors, six journal editors, three nurses and four public members, some of whom had multiple roles, e.g. doctor and academic. Participants were distributed over four continents, mostly from Europe (n=39). Both Australia and America had identical representation (n=8), while two participants represented Asia. Consensus was reached following the third round on seven outcomes, namely: medication adherence across multiple medications (100.0%), treatment burden (96.2%), health-related quality of life (96.2%), healthcare utilisation (83.0%), adverse events and side effects (83.0%), patient-carer satisfaction (82%), and cost-effectiveness (81.1%). Conclusion Seven outcomes were considered of critical importance to stakeholders. This study is the first to develop a COS for interventions targeting adherence to appropriate polypharmacy in older patients. However, most of our participants were academics and pharmacists from Europe, whilst other participant categories and continents were less well-represented. A future nominal group technique study will be conducted to discuss the results obtained from previous Delphi questionnaires, followed by selecting the appropriate outcome measurement instruments to measure these outcomes. References 1. Cross AJ, Elliott RA, Petrie K et al. Interventions for improving medication-taking ability and adherence in older adults prescribed multiple medications. Cochrane Database Syst Rev 2020; 5: CD012419. 2. Williamson PR, Altman DG, Bagley H et al. The COMET Handbook: version 1.0. Trials 2017; 18: 280–330.