Cunningham, Colm M.

AbstractBACKGROUNDDelirium, a common syndrome with heterogeneous etiologies and clinical presentations, is associated with poor long‐term outcomes. Recording and analyzing all delirium equally could be hindering the field's understanding of pathophysiology and identification of targeted treatments. Current delirium subtyping methods reflect clinically evident features but likely do not account for underlying biology.METHODSThe Delirium Subtyping Initiative (DSI) held three sessions with an international panel of 25 experts.RESULTSMeeting participants suggest further characterization of delirium features to complement the existing Diagnostic and Statistical Manual of Mental Disorders Fifth Edition Text Revision diagnostic criteria. These should span the range of delirium‐spectrum syndromes and be measured consistently across studies. Clinical features should be recorded in conjunction with biospecimen collection, where feasible, in a standardized way, to determine temporal associations of biology coincident with clinical fluctuations.DISCUSSIONThe DSI made recommendations spanning the breadth of delirium research including clinical features, study planning, data collection, and data analysis for characterization of candidate delirium subtypes.Highlights Delirium features must be clearly defined, standardized, and operationalized. Large datasets incorporating both clinical and biomarker variables should be analyzed together. Delirium screening should incorporate communication and reasoning.

Despite many studies of potential delirium biomarkers, delirium pathophysiology remains unclear. Evidence shows that the quality of reporting delirium biomarker studies is sub-optimal. Better reporting of delirium biomarker studies is needed to understand delirium pathophysiology better. To improve robustness, transparency and uniformity of delirium biomarker study reports, the REDEEMS (Reporting Essentials for DElirium bioMarker Studies) guideline was developed by an international group of delirium researchers through a three-stage process, including a systematic review, a three-round Delphi study, and a follow-up consensus meeting. This process resulted in a 9-item guideline to inform delirium fluid biomarker studies. To enhance implementation of the REDEEMS guideline, this Explanation and Elaboration paper provides a detailed explanation of each item. We anticipate that the REDEEMS guideline will help to accelerate our understanding of delirium pathophysiology by improving the reporting of delirium biomarker research and, consequently the capacity to synthesise results across studies.