Jean-Baptiste Beuscart, Olivia Dalleur, Benoit Boland, Stefanie Thevelin, Wilma Knol, Shane Cullinan, Claudio Schneider, Denis O’Mahony, Nicolas Rodondi, Anne Spinewine

Medication review has been advocated to address the challenge of polypharmacy in older patients, yet there is no consensus on how best to evaluate its efficacy. Heterogeneity of outcomes reported in clinical trials can hinder the comparison of clinical trial findings in systematic reviews. Moreover, the outcomes that matter most to older patients might be under-reported or disregarded altogether. A core outcome set can address this issue as it defines a minimum set of outcomes that should be reported in all clinical trials in any particular field of research. As part of the European Commission-funded project, called OPtimising thERapy to prevent Avoidable hospital admissions in the Multimorbid elderly, this paper describes the methods used to develop a core outcome set for clinical trials of medication review in older patients with multimorbidity. The study was designed in several steps. First, a systematic review established which outcomes were measured in published and ongoing clinical trials of medication review in older patients. Second, we undertook semistructured interviews with older patients and carers aimed at identifying additional relevant outcomes. Then, a multilanguage European Delphi survey adapted to older patients was designed. The international Delphi survey was conducted with older patients, health care professionals, researchers, and clinical experts in geriatric pharmacotherapy to validate outcomes to be included in the core outcome set. Consensus meetings were conducted to validate the results. We present the method for developing a core outcome set for medication review in older patients with multimorbidity. This study protocol could be used as a basis to develop core outcome sets in other fields of geriatric research.