Antimicrobial stewardship in care homes for older people
: Development of a core outcome set

  • Hoa Nguyen

Student thesis: Doctoral ThesisDoctor of Philosophy


Heterogeneity of outcomes measured in trials to improve antimicrobial stewardship (AMS) in care homes has impeded synthesising evidence and producing definitive conclusions. This thesis aimed to develop a core outcome set (COS) for use in trials focusing on improving AMS in care homes.

The research presented in this thesis followed current guidelines for development of a COS (COMET) and selection of outcome measurement instruments (OMIs) for the COS (COSMIN). A systematic review was conducted to evaluate the effectiveness of randomised controlled trials (RCTs) to improve AMS in care homes and to determine outcomes reported in these studies. A qualitative study was undertaken to explore outcomes deemed important to key stakeholders comprising researchers, healthcare professionals, and family members of care home residents. Subsequently, a series of consensus procedures with relevant stakeholders were carried out to reach consensus on outcomes that should be included in the COS for use in trials aimed at improving AMS in care homes. Finally, methodology suggested by the COSMIN guidelines was followed to select OMIs available in the literature for outcomes in the COS.

The systematic review identified six RCTs with 28 outcomes reported and found the interventions had limited effect on improvement of antimicrobial prescribing. Interviews with 41 key stakeholders in the qualitative study revealed 49 outcomes that were deemed important to them, including 40 additional outcomes which had not been used in previous RCTs. Outcomes identified in the systematic review and the qualitative study were reviewed and refined by the research team to produce an inventory of 14 outcomes. This inventory was presented in an online Delphi survey with 82 participants from 17 different countries, followed by an online consensus exercise with 12 participants in Northern Ireland. Consensus was reached to include five outcomes in the COS, comprising two main outcomes (‘The total number of antimicrobial courses prescribed’ and ‘Appropriateness of antimicrobial prescribing’) and three optional outcomes (‘Days of therapy per 1000 resident-days’, ‘Rate of antimicrobial resistance’, and ‘Mortality related to infection’). Following the COSMIN approach, 17 potential OMIs for the COS identified in literature searches were assessed for quality of measurement properties. Three OMIs with the best quality of evidence were presented in a consensus exercise with 59 Delphi panel members from 16 different countries. Ultimately, consensus was reached to select two OMIs for two outcomes ‘The total number of antimicrobial courses prescribed’ and ‘Days of therapy per 1000 resident-days’ in the COS. No OMIs were selected for the other outcomes in the COS.

The research described in this thesis developed a COS for use in trials aimed at improving AMS in care homes. Future studies should use this COS to measure the effectiveness and safety of AMS interventions in care homes.
Date of AwardDec 2020
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SponsorsVietnam International Education Development
SupervisorMichael Tunney (Supervisor) & Carmel Hughes (Supervisor)


  • antimicrobial stewardship
  • care homes
  • core outcome set (COS)
  • outcome measurement instrument (OMI)

Cite this