Acknowledgments Ellen Murphy and Genevieve Shiely Hayes for their contributions to data collection. Funding: MB was funded for a summer period by the Health Research Board, Ireland through funding from the HRB Trials Methodology Research Network (Ref: HRB TMRN-2017-1). The Health Services Research Unit, Institute of Applied Health Sciences (University of Aberdeen), is core-funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorates (CZU/3/3). The funders had no involvement in study design, collection, analysis and interpretation of data, reporting or the decision to publish.Peer reviewedPublisher PD