Detecting Delirium and Subsyndromal Delirium Using Different Diagnostic Criteria among Demented Long-Term Care Residents

Objectives: To evaluate the impact of using different diagnostic criteria on prevalence rates of delirium and subsyndromal delirium (SSD) among demented long-term care (LTC) residents. Design: Descriptive study. Setting: LTC settings in Quebec City, Canada. Participants: Participants were 155 individuals aged 65 and older, with dementia. Measurements: (1) Prevalence rates of delirium according to: (a) the Diagnostic and Statistical Manual of Mental Disorders (DSM-III, DSM-III-R, and DSM-IV) and (b) the Confusion Assessment Method (CAM) algorithms for definite and probable delirium; and (2) prevalence rates of SSD employing 2 definitions described in previous studies. Results: Prevalence rates of delirium according to each set of criteria were 26.5% for DSM-III; 29% for DSM-IV-TR; 41.3% for DSM-III-R; 45.8% for CAM algorithm for definite delirium; and 70.3% for CAM algorithm for probable delirium. A total of 109 subjects (70.3%) were identified as delirious consistent with at least one classification and 37 (23.9%) met all the sets of criteria considered. Prevalence rates for SSD were 75 (48.4%) and 78 (50.3%) depending on the definition employed. Conclusion: Prevalence rates for delirium are much affected by the diagnostic formulations used. The use of DSM-IV-TR among this population could result in fewer cases being identified as delirious and thus compromise proper care for those individuals. Considering that SSD was prevalent among this population, a systematic implementation of protocols targeting risk factors of delirium might be beneficial among demented LTC residents. (J Am Med Dir Assoc 2009; 10: 181-188)