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Reference: Ann Intern Med 2014 Apr 15;160(8):526 (level 2 [mid-level] evidence)
Hospitalized patients are at an increased risk of delirium, with incidence rates ranging from 3%-29% for new-onset delirium during hospitalization (Age Ageing 2006 Jul;35(4):350 full-text). The Confusion Assessment Method (CAM) is a validated assessment tool that has been shown to reliably identify delirium in several different patient populations (J Am Geriatr Soc 2008 May;56(5):823 full-text), and may be used in screening for delirium on hospital admission. A recent prospective cohort study evaluated a new CAM-Severity (CAM-S) score to predict adverse outcomes in hospitalized patients ≥ 70 years old without delirium on admission.
The derivation cohort included 300 patients ≥ 70 years old from the Successful Aging After Elective Surgery (SAGES) study who were scheduled for major surgery and did not have delirium on hospital admission. The validation cohort included 919 similar hospitalized patients from the Project Recovery study. An additional 355 eligible patients were excluded from the validation cohort for unexplained reasons.
The CAM-S short form score was derived using factors from CAM diagnostic assessment tool (total score 0-7 points):
- acute onset or symptom fluctuation (1 point if present)
- inattention (1 point if mild or 2 points if marked)
- disorganized thinking (1 point if mild or 2 points if marked)
- altered level of consciousness (1 point if mild or 2 points if marked)
The CAM-S score was used to categorize patients into 4 different risk groups: none (0 points), low (1 point), moderate (2 points), and high (3-7 points). In the validation cohort, 90-day mortality was 7% among 598 patients with no risk factors, 15% among 91 patients in the low risk category, 16% among 128 patients in the moderate risk category, and 27% among 102 in the high risk category (p for trend < 0.001). Similarly, adjusted mean length of hospital stay was 6.5 days with no risk factors, 8.8 days for the low risk category, 11.1 days for the moderate risk category, and 12.7 days for the high risk category (p for trend < 0.001). Increased CAM-S short form scores were also associated with increased risk of new nursing home placement, functional decline, and cognitive decline (p for trend < 0.001 for each). The prediction of adverse patient outcomes with the CAM-S short form was also consistent with a 10-item long form of CAM-S (total score 0-19 points).
Although the use of CAM and related diagnostic assessment tools have proved to be helpful for diagnosing delirium in high-risk populations, using the data from the screening assessment to predict adverse outcomes has not been previously described. The findings of this cohort study show that the CAM-S short form score can help predict important patient outcomes such as 90-day mortality and hospital duration, among others. There were some differences in patient characteristics between the derivation and validation cohorts in the study, which may be viewed as a limitation but may also indicate the generalizability of the findings to different patient populations. Altogether, this new tool provides useful information that may help predict adverse outcomes, guide treatment decisions, and potentially monitor response to treatment in some patient populations.
For more information see the Delirium topic in DynaMed.
Special thanks to Sara Martin and Anna Pancheshnikov for their contributions to this week’s article.