ORCHARD-PS: Baseline delirium occurrence, subtypes, and associations with cognition and frailty in a prospective cohort

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Jasmine Gan1; Lily Elderton1; Athena Yu2; Caio Guerra Hansen2; Sanchit Turaga1; Aubretia McColl3; Sarah T Pendlebury1,4

1 University of Oxford,2 Oxford (Thames Valley) Foundation School,3 Royal Berkshire NHS Foundation Trust, 4 Oxford University Hospitals NHS Foundation Trust

Scientific Research

SP- Planned and ongoing trials

Delirium

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Abstract

Introduction

The Oxford and Reading Cognitive Health After Recovery from acute illness and Delirium- Prospective Study (ORCHARD-PS) aims to investigate the pathophysiology of delirium and future dementia risk after acute illness (Gan JM, Elderton L, Vijayakumar Sheela M, et al. BMJ Open, 2025 Jun 13;15(6):e102028). We determined baseline delirium occurrence, delirium subtype and associations with cognition and frailty in an interim analysis.

Methods

Acute medical patients aged 65 years and older without terminal illness, advanced dementia or nursing home residence were enrolled after consent/consultee agreement. Delirium was diagnosed by DSM-V criteria and subsyndromal delirium (SSD) if full criteria were not met. Delirium was categorised by motoric subtype with severity measured using the Memorial Delirium Assessment Scale (MDAS). Montreal Cognitive Assessment (MoCA<26=abnormal) and the Clinical Frailty Scale (CFS>4=frail) were performed.

Results

Of 204 participants (mean age/SD=82.3/6.7 years, 99 [49%] female, 35 [17%] consultee declaration, 14[7%] co-morbid dementia), delirium occurred in 41 (20%) and 23 (11%) had SSD. Hypoactive delirium was more common than hyperactive and mixed delirium (22/41[54%] vs 14/41 [34%] vs 5/41[12%], p=0.005). The MDAS score ranged from 0-20 and was higher in delirium/SSD vs no delirium (median MDAS 4 [IQR1-7] vs 2 [IQR 0-3], p<0.001]. MoCA was lower in delirium/SSD vs no delirium (median MoCA 18 [IQR 13-22] vs 23 [IQR 19-25], p<0.001). Abnormal MoCA and frailty were more common in delirium/SSD vs no delirium (abnormal MoCA: 54/56[96.4%] vs 103/136[76%], p<0.001; frailty: 46/64[72%] vs 49/140[35%], p<0.001).

Conclusions

One third of ORCHARD-PS participants had delirium/SSD. Hypoactive delirium accounted for half of delirium cases and cognitive and physical frailty was prevalent. Our target sample of 620 will provide 195 delirium/SSD cases for future multimodal biomarker studies on which data are currently scarce.