Exploring the association between medication, patient-specific factors and delirium in hospitalised patients: a 10-year retrospective, population-based cohort study in Iceland

Objectives This study aimed to identify potential significant statistical associations between the development of delirium, medication and several other patient-specific factors across a 10-year retrospective longitudinal real-world dataset. Design A retrospective, population-based cohort study.

Setting The National University Hospital of Iceland. Participants All patients≥18 years hospitalised between 2010 and 2020.

Primary and secondary outcome measures The primary outcome was a diagnosis of delirium within 2 years of a patient filling a prescription for a specific medication. The exposure was pre-admission medication use or a pre-existing condition.

Secondary outcomes included mortality, length of hospital stay, readmission rate and frequency of additional delirium diagnosis. Results A total of 85 942 admissions and readmissions were included in the dataset, which comprised 1066 variables.

The cohort comprised 55 495 patients (51.5% male) with a median [IQR] age of 71 years [58, 82]. Throughout the study, 3533 patients were diagnosed with delirium at least once over the 10-year study period.