CAP Properties

Reliability: The CAP is still in an early stage of development and specific reliability studies have not yet been conducted. However, all but 2 CAP items (Sleep-disturbance and Level of Arousal/Daytime Drowsiness) were taken from previously developed scales. Data regarding the reliability of these scales may pertain to the CAP. These data may be found by reviewing articles on the original scales. Complete references for these scales can be found in the Reference section.

Validity: Preliminary concurrent validity for the CAP has been assessed by comparing classification as confused (in PCS) vs. non-confused (not in PCS) to classification as in delirium vs. not in delirium based on DSM-IV criteria. Sherer, Nakase-Thompson, and Yablon (2003) studied 62 patients with moderate or severe TBI at admission to inpatient rehabilitation. Findings revealed that 44 (71%) of patients met CAP criteria for confusion while 40 (64%) met DSM-IV criteria for delirium at admission to inpatient rehabilitation. Of the 44 confused patients, 38 also met criteria for delirium and of the 40 delirious patients, 38 also met criteria for confusion. Overall agreement was 87%.

Sherer, Nakase-Thompson, Nick, and Yablon (2003) performed a cluster analysis on the same sample of 62 patients. Two distinct patterns of confusion emerged. Patients in one cluster were all agitated and showed a high incidence of psychotic-type symptoms. Patients in the other confused cluster showed no restlessness and a much lower incidence of psychotic-type symptoms. Patients in this second cluster were very likely to have decreased day-time arousal. Patients in both clusters had high incidences of disorientation, cognitive impairment, and symptom fluctuation.

The present validity data are preliminary. Additional research is needed to replicate and extend these findings. The finding of distinct patterns of confusion may have treatment implications. The ability of the CAP to capture a wide range of symptoms of confusion makes it well suited as an outcome measure in clinical trials of treatments for confusion.