Core outcome set for studies evaluating interventions to prevent or treat delirium in long-term care older residents:international key stakeholder informed consensus study

BACKGROUND: Trials of interventions to prevent or treat delirium in older adults resident in long-term care settings (LTC) report heterogenous outcomes, hampering the identification of effective management strategies for this important condition. Our objective was to develop international consensus among key stakeholders for a core outcome set (COS) for future trials of interventions to prevent and/or treat delirium in this population. METHODS: We used a rigorous COS development process including qualitative interviews with family members and staff with experience of delirium in LTC; a modified two-round Delphi survey; and virtual consensus meetings using nominal group technique. The study was registered with the Core Outcome Measures in Effectiveness Trials (COMET) initiative (https://www.comet-initiative.org/studies/details/796). RESULTS: Item generation identified 22 delirium-specific outcomes and 32 other outcomes from 18 qualitative interviews. When combined with outcomes identified in our earlier systematic review, and following an item reduction step, this gave 43 outcomes that advanced to the formal consensus processes. These involved 169 participants from 12 countries, and included healthcare professionals (121, 72%), researchers (24, 14%), and family members/people with experience of delirium (24, 14%). Six outcomes were identified as essential to include in all trials of interventions for delirium in LTC, and were therefore included in the COS. These are: 'delirium occurrence'; 'delirium related distress'; 'delirium severity'; 'cognition including memory', 'admission to hospital' and 'mortality'. CONCLUSIONS: This COS, endorsed by the American Delirium Society and the European and Australasian Delirium Associations, is recommended for use in future clinical trials evaluating delirium prevention or treatment interventions for older adults residing in LTC.