Table 3 Source items and indicator IRT parameters for top five indicators identified for each dimension of each CAM feature*
From: Selecting optimal screening items for delirium: an application of item response theory
Feature and Indicator Selection (top five indicators) | Discrimination | Difficulty |
|---|---|---|
threshold level(θ 50 +) on latent trait | (a) | (b) |
Feature 1 -Acute Change and Fluctuating Course- Direct interview (θ 50 + = − 0.20) | ||
Felt confused during the past day | 0.96 | 1.72 |
Thought you were not really in (name of facility) | 1.00 | 2.21 |
Saw things that were not really there | 1.33 | 2.29 |
Thought things were moving that were not really moving | 0.98 | 2.66 |
Heard things that were not really there | 1.55 | 2.56 |
Feature 1 -Acute Change and Fluctuating Course-Observational (θ 50 + = 1.17) | ||
Level of consciousness fluctuated | 2.97 | 1.80 |
Level of attention fluctuated | 1.83 | 1.46 |
Speech/thinking fluctuated | 1.98 | 1.77 |
Evidence of disturbance of sleep | 1.97 | 1.83 |
Psychomotor activity fluctuated | 1.57 | 2.43 |
Feature 2 -Inattention- Direct interview First Factor (θ 50 + = 0.22) | ||
What is the year? †| 1.57 | 1.14 |
What is the month? †| 1.86 | 1.17 |
What is the day of the week? †| 1.21 | 0.78 |
What type of place is this? †| 1.55 | 1.23 |
What is the name of this place? †| 1.12 | 0.24 |
Second Factor (θ 50 + = 0.27) | ||
Days of the week backwards | 1.65 | 1.29 |
Months of the year backwards | 1.17 | 0.20 |
Digit span backwards 3 Numbers ‡ | 1.12 | 0.85 |
Digit span backwards 4 Numbers ‡ | 1.20 | −0.34 |
Digit span forwards 4 Numbers ‡†| 1.11 | 2.09 |
Feature 2 -Inattention- Observational (θ 50 + = 0.38) | ||
Trouble keeping track of what was being said | 1.26 | 0.25 |
Level of attention fluctuated | 1.74 | 1.55 |
Unaware of environment | 2.09 | 1.91 |
Distracted by environmental stimuli | 1.28 | 2.06 |
Staring into space | 1.09 | 2.11 |
Feature 3 -Disorganized Thinking Direct interview (θ 50 + = 0.67) | ||
What type of place is this?†| 1.56 | 1.23 |
What is the year? †| 1.49 | 1.17 |
What is the month? †| 1.74 | 1.20 |
What is the day of the week? †| 1.20 | 0.79 |
What is the name of this place? †| 1.11 | 0.24 |
Feature 3 -Disorganized Thinking Observational § First Factor (θ 50 + = 1.03) | ||
Unclear or illogical flow of ideas | 2.07 | 1.29 |
Changes the subject suddenly | 1.83 | 1.90 |
Conversation was rambling | 1.36 | 1.68 |
Words or phrases that were disjointed or inappropriate | 1.33 | 2.21 |
Speech/thinking fluctuated | 1.17 | 2.27 |
Feature 4 -Fluctuating Course and Altered Level of Consciousness- Observational First Factor (θ 50 + = 1.99) | ||
Sleepy, or stuporous, or comatose | 9.70 | 1.70 |
Disturbance of sleep | 3.18 | 1.81 |
Lethargy and sluggishness | 1.41 | 1.44 |
Slowness of motor response | 1.23 | 1.70 |
Expressed a paucity of thoughts | 0.97 | 3.23 |
Second Factor (θ 50 + = − 0.14) | ||
Restlessness | 1.44 | 2.02 |
Speech unusually fast or pressured | 0.74 | 3.71 |
Excessive absorption with ordinary objects | 2.31 | 2.29 |
Increased speed of motor response | 0.69 | 4.49 |
Grasping/picking | 2.68 | 2.20 |