Objective: To evaluate the diagnostic accuracy of tools to identify delirium in inpatients with Parkinson’s disease (PD).

Background: Delirium is a serious acute state of confusion that commonly occurs in PD and PD dementia and includes symptoms of altered sleep, impaired attention, hallucinations, and delusions. Overlapping symptoms makes delirium difficult to identify in PD and the diagnosis of delirium is often missed in hospital. Current tools used to assess for delirium have not been validated in PD.

Method: People with PD admitted acutely or electively to all hospital wards in Newcastle were invited to take part. Delirium was classified using a standardised assessment based on the Diagnostic and Statistical Manual of Mental Disorders 5th Edition (DSM-5) criteria, comprising objective testing, observations and detailed collateral history from participants’ family/carer, hospital staff and medical notes. Participants were assessed daily for up to five days. We applied the 4 As Test (4AT) (score≥4 indicated delirium), Confusion Assessment Method (CAM), the Single Question in Delirium (SQUiD), the Memorial Delirium Assessment Scale (MDAS≥13 indicated delirium) and the Delirium Rating Scale (DRS-R-98>15 indicated delirium). Measures were evaluated against the gold standard diagnosis using DSM-5 criteria using Receiver Operating Characteristic area under the curve (AUC), sensitivity, specificity, and accuracy were calculated.

Results: Participants included n=115 people with PD, comprising 199 hospital admissions. Of these, 66.1% (n=76/115) had delirium. Accuracy of tests ranged from 74-89% (AUC=0.764-0.923, p<0.01 for all). Sensitivity ranged from 66.9-96.7% with specificity of 73.1-96.2%. The MDAS score had the highest AUC (AUC=0.923, p<0.001, MDAS≥13 sensitivity 78.5%, specificity 89.7%, accuracy 82.9%), followed by the 4AT score (AUC=0.922, p<0.001, score≥4 sensitivity 96.7%, specificity 73.1%, accuracy 87.4%).

Conclusion: Delirium is common in PD. Although the MDAS was the most accurate tool, the 4AT had higher sensitivity and diagnostic accuracy, and therefore may have better clinical utility as a screening tool. The 4AT is also quicker to complete and is already in widespread clinical use. However, caution is recommended as tools did not differentiate between PD features and acute symptoms associated with delirium. A PD specific delirium measure may be helpful for future delirium management and clinical trials.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/identifying-delirium-in-parkinsons-evaluation-of-existing-tools-and-measures/