Protocol for a process evaluation of an external pilot cluster randomised controlled trial of a theory-based intervention to improve appropriate polypharmacy in older people in primary care: the PolyPrime study.

<bold>Background: </bold>The PolyPrime intervention is a theory-based intervention aimed at improving appropriate polypharmacy in older people (aged ≥65 years) in primary care. The intervention consists of an online video which demonstrates how general practitioners (GPs) can prescribe appropriate polypharmacy during a consultation with an older patient and a patient recall process, whereby patients are invited to scheduled medication review consultations with GPs. The aim of the process evaluation is to further examine the implementation of the PolyPrime intervention in primary care. This will involve investigating whether the PolyPrime intervention can be delivered as intended across two healthcare systems, how acceptable the intervention is to GPs, practice staff and patients, and to identify the intervention's likely mechanisms of action.<bold>Methods: </bold>The PolyPrime study is an external pilot cluster randomised controlled trial (cRCT) which aims to recruit 12 GP practices across Northern Ireland [NI] (n=6) and the six counties in the Republic of Ireland (ROI) that border NI (n=6). Practices have been randomised to intervention or usual care. An embedded process evaluation will assess intervention fidelity (i.e. was the intervention delivered as intended), acceptability of the intervention to GPs, practice staff and patients and potential mechanisms of action (i.e. what components of the intervention were perceived to be effective). Quantitative data will be collected from data collection forms completed by GPs and practice staff and a feedback questionnaire completed by patients from intervention arm practices, which will be analysed using descriptive statistics. Qualitative data will be collected through semi-structured interviews with GPs and practice staff and audio-recordings of medication review appointments from the intervention arm practices which will be transcribed and analysed using the framework method. Quantitative and qualitative data will be triangulated to provide an overall assessment of intervention fidelity, intervention acceptability, and mechanisms of action.<bold>Discussion: </bold>This process evaluation will add to feasibility data from the pilot cRCT by providing evidence on the fidelity of implementing the intervention package across two healthcare systems, the acceptability of the intervention and potential mechanisms of action.<bold>Trial Registration: </bold>ClinicalTrials.gov ISRCTN41009897 . Registered on 19 November 2019. ClinicalTrials.gov NCT04181879 . Registered 02 December 2019. [ABSTRACT FROM AUTHOR]