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Figure 2 | BMC Medical Research Methodology

Figure 2

From: Selecting optimal screening items for delirium: an application of item response theory

Figure 2

This figure plots the item information curves for all direct interview based indicators identified by the clinical consensus panel as measures of CAM feature 2 - inattention. Parameters were estimated from analysis of delirium screening data for 4,598 persons evaluated for inclusion in the DAP Trial [38]. Two lines are highlighted: ″List the months of the year backwards.″ (heavy dotted line) and ″List the days of the week backwards.″ (solid bolded line). Box and whisker plots show distributions of estimates of latent trait scores for participants classified as CAM feature 2 - inattention positive and negative by the CAM algorithm (see text for details). Vertical reference lines for key percentiles of the feature positive group are illustrated in the main panel. Note that the whiskers identify the minimum and maximum in this group. Among all the indicators evaluated, the two highlighted indicators have the maximum information content at the 50th percentile of the population of patients who had Feature 2, Inattention, coded as present, and therefore represent indicators with optimal screening efficiency for the presence of inattention.

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