Development and feasibility of a smartphone-based test for the objective detection and monitoring of attention impairments in delirium in the ICU

Purpose: Delirium in the ICU is under-diagnosed. We evaluated feasibility and performance of a novel smartphone-based test for objectively detecting inattention in delirium. Material and methods: DelApp-ICU combines a behavioural assessment and an attention task, whereby participants follow simple commands and count serially presented circles (score range 0–12, lower scores indicating worse performance). We assessed feasibility through staff interviews. Then we performed a preliminary case-control study in patients with and without delirium (ascertained with the Confusion Assessment Method for the ICU) who underwent the DelApp-ICU on up to 4 days. Results: Forty-six patients (median age = 57.5 years, range 18–83) were assessed 89 times in total (N's = 46, 29, 10 and 4 for subsequent assessments; 33.7% delirious). DelApp-ICU scores were lower in delirium (N = 20; median = 0.5, Inter-Quartile Range (IQR) = 0–4.75) compared to no delirium (N = 26, median = 12, IQR = 8–12) on days 1, 2 and 3 (p < 0.001, p < 0.001 and p < 0.05, respectively). A DelApp-ICU score ≤6 was 100% sensitive and 96% specific to delirium on day 1. Positive and Negative Predictive Values were 91% and 100%, respectively. DelApp-ICU scores were responsive to changes in CAM-ICU status. Conclusions: DelApp-ICU shows promise for assessing inattention and delirium in ICU patients, including longitudinally monitoring deficits and providing a metric of delirium severity.