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Prediction score: functional status and dehydration predict delirium in hospitalized elders

Clinical Question:
How well does a prediction score predict incident delirium in hospitalized elders?

Bottom Line:
A prediction score using the Barthel index (a measure of independence in basic activities of daily living) and the ratio of blood urea nitrogen (BUN) to creatinine can serve as the basis for identifying hospitalized elderly patients at risk of developing delirium. (LOE = 1b)

Carrasco MP, Villarroel L, Andrade M, Calderón J, González M. Development and validation of a delirium predictive score in older people. Age Ageing 2014;43(3):346-351.  [PMID:24064236]

Study Design:
Decision rule (validation)


Inpatient (any location)

These Chilean authors independently studied 2 consecutive cohorts of patients 65 years or older who were admitted to general hospital wards. They excluded patients with severe aphasia, those in a coma, and those unable to perform cognitive assessments. A psychogeriatric team (NOT a psycho geriatric team!) evaluated each patient within 48 hours of admission and then every 48 hours until discharge. They used a structured approach to establishing the presence or absence of delirium based on information provided by the patient and caregivers. The 2 cardinal features to establishing the diagnosis of delirium were (1) acute onset and fluctuating course, and (2) inattention and either disorganized thinking or altered levels of consciousness. The team assessed multiple factors—clinical and laboratory—in 374 patients and then played a bunch of statistical games to develop a statistical model that predicts the development of delirium. They then validated this model on a second cohort of 104 hospitalized elders who were assessed in a manner similar to the development cohort. Among the development cohort, 25 patients (6.7%) developed delirium. among the validation cohort, 12 of the 104 patients developed delirium. Two factors—the Barthel index and the BUN:creatinine ratio—became the basis for their Delirium Predictive Risk Score (DPS): (1370 x BUN (mmol/L)/creatinine (mmol/L) minus (4 x Barthel index)* For the development cohort, the area under the receiving operator characteristic curve (a measure of test performance) was 0.86 (95% CI, 0.82 - 0.91). A score over ?240 was associated with a 45% chance of developing delirium. The scale was decent at identifying patients unlikely to develop delirium (negative likelihood ratio = 0.16; 0.06 - 0.47), but only modestly reliable in predicting those who will develop delirium (positive likelihood ratio = 3.4; 2.8 to 4.1). When they tested how the model performs in the validation cohort, the score's overall accuracy was approximately the same as in the development cohort (0.78; 0.66 - 0.90). * when using non-SI units, the cut point is ?160 and the formula for the score is: (5 × BUN (mg/dL)/creatinine (mg/dL) minus (3 × Barthel index) Unrelated bonus material: If you have any interest in the World Cup, or even if you don’t, the Chilean team's promotion is truly inspiring. Here is a link: http://www.youtube.com/watch?v=tmLmWiqSVS8. Non-Spanish speakers turn on the closed captioning.


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