Development of a core outcome set for clinical trials aimed at improving antimicrobial stewardship in care homes

Diverse outcomes reported in clinical trials of antimicrobial stewardship (AMS) interventions in care homes have hindered evidence synthesis. Our main objective was to develop a core outcome set (COS) for use in trials aimed at improving AMS in care homes.

A refined inventory of outcomes for AMS interventions in care homes, compiled from a previous study, was rated in a three-round international Delphi survey with 82 participants, using a nine-point Likert scale (from 1, unimportant, to 9, critical). This was followed by an online consensus exercise with 12 participants from Northern Ireland to finalise the COS content. Subsequently, a suitable outcome measurement instrument (OMI) was selected for each outcome in the COS by: identifying existing OMIs through a literature search and experts' suggestions, assessing the quality of OMIs, and selecting one OMI for each core outcome via a two-round international Delphi survey with 59 participants.

Of 14 outcomes initially presented, consensus was reached for inclusion of five outcomes in the COS after the three-round Delphi survey and the online consensus exercise, comprising the total number of antimicrobial courses prescribed, appropriateness of antimicrobial prescribing, days of therapy per 1000 resident-days, rate of antimicrobial resistance, and mortality related to infection. Of 17 potential OMIs identified, three were selected for the two-round Delphi exercise after the quality assessment. Consensus was reached for selection of two OMIs for the COS.

This COS is recommended to be used in clinical trials aimed at improving AMS in care homes.