The course of subsyndromal delirium in older long-term care residents

To determine the course of incident subsyndromal delirium (SSD) in older long-term care (LTC) residents. A secondary objective was to explore the use of a more restrictive definition of SSD on the findings of the study.

Cohort study with repeated weekly assessments for up to 6 months.

Seven LTC facilities in Montreal and Quebec City, Canada.

LTC residents aged 65 and more and free of delirium core symptoms at baseline.

The Mini-Mental State Examination (MMSE), Confusion Assessment Method (CAM), Delirium Index (DI), Hierarchic Dementia Scale, and Barthel Index were completed at baseline. The MMSE, CAM, and DI were repeated weekly for 6 months. SSD1 required one or more CAM core symptoms; SSD2, a more restrictive definition, required two or more CAM core symptoms.

Sixty-eight residents had 129 incident episodes of SSD1: 32 had one episode and 36 had two or more episodes. Episodes lasted 7 - 133 days, mean 13.7 (SD: 14.8) days; mean number of symptoms per episode was 1.1 (SD: 0.4). Rates of recovery at 1, 2, and 4 weeks and 6 months were 45.7%, 61.2%, 64.6%, and 78.3%, respectively. Thirty-three residents had 49 episodes of SSD2: 21 had 1 episode and 12 had 2 or more episodes. Use of the more restrictive definition significantly increased time to recovery and reduced rate of recovery.

Episodes of SSD in older LTC residents appeared to last 7-133 days (mean: 13.7) and were often recurrent. Use of a more restrictive definition resulted in a more protracted course.