The CAM-S: development and validation of a new scoring system for delirium severity in 2 cohorts

Abstract

Background: Quantifying the severity of delirium is essential to advancing clinical care by improved understanding of delirium effect, prognosis, pathophysiology, and response to treatment.

Objective: To develop and validate a new delirium severity measure (CAM-S) based on the Confusion Assessment Method.

Design: Validation analysis in 2 independent cohorts.

Setting: Three academic medical centers.

Patients: The first cohort included 300 patients aged 70 years or older scheduled for major surgery. The second included 919 medical patients aged 70 years or older.

Measurements: A 4-item short form and a 10-item long form were developed. Association of the maximum CAM-S score during hospitalization with hospital and posthospital outcomes related to delirium was evaluated.

Results: Representative results included adjusted mean length of stay, which increased across levels of short-form severity from 6.5 days (95% CI, 6.2 to 6.9 days) to 12.7 days (CI, 11.2 to 14.3 days) (P for trend < 0.001) and across levels of long-form severity from 5.6 days (CI, 5.1 to 6.1 days) to 11.9 days (CI, 10.8 to 12.9 days) (P for trend < 0.001). Representative results for the composite outcome of adjusted relative risk of death or nursing home residence at 90 days increased progressively across levels of short-form severity from 1.0 (referent) to 2.5 (CI, 1.9 to 3.3) (P for trend < 0.001) and across levels of long-form severity from 1.0 (referent) to 2.5 (CI, 1.6 to 3.7) (P for trend < 0.001).

Limitation: Data on clinical outcomes were measured in an older data set limited to patients aged 70 years or older.

Conclusion: The CAM-S provides a new delirium severity measure with strong psychometric properties and strong associations with important clinical outcomes.

Primary funding source: National Institute on Aging.

Figure 1. Distribution of CAM-S by Delirium Status in Total Sample and Stratified by Dementia Status

* The maximal CAM-S score during each patient’s hospitalization was used in all analyses. Boxes around the plots represent the median, 25^th, and 75^th percentiles. If a box is not shown, that indicates the median, 25^th and 75^th percentile all had the same value. The stratified analyses by dementia group were conducted in Project Recovery (PR).

Appendix Figure 1. CAM-S Scores by Length of Stay*

*Plots of maximal CAM-S scores per patient by length of hospital stay. The green line runs through fitted values derived from log-gamma regression.

Appendix Figure 2. CAM-S Scores by Hospital Costs

*Plots of maximal CAM-S scores per patient by hospital costs. The green line runs through fitted values derived from log-gamma regression.

Appendix Figure 3. CAM-S Scores by New Nursing Home Placement*

* The maximal CAM-S score during each patient’s hospitalization was used in all analyses. Boxes around the plots represent the median, 25^th, and 75^th percentiles. If a box is not shown, that indicates the median, 25^th and/or 75^th percentile all had the same value.

Appendix Figure 4. CAM-S Scores by Functional Decline*

* The maximal CAM-S score during each patient’s hospitalization was used in all analyses. Functional decline was defined as a decline of 2 or more points of 14 points in activities of daily living between baseline and discharge scores (see text for details). Boxes around the plots represent the median, 25^th, and 75^th percentiles. If a box is not shown, that indicates the median, 25^th and/or 75^th percentile all had the same value.

Appendix Figure 5. CAM-S Scores by Cognitive Decline*

* The maximal CAM-S score during each patient’s hospitalization was used in all analyses. Cognitive decline defined as a decline by 2 or more points in Mini-Mental Status Examination Score between baseline and discharge. Boxes around the plots represent the median, 25^th, and 75^th percentiles. If a box is not shown, that indicates the median, 25^th and/or 75^th percentile all had the same value.

Appendix Figure 6. CAM-S Scores by Death within 90 Days

* The maximal CAM-S score during each patient’s hospitalization was used in all analyses. Boxes around the plots represent the median, 25^th, and 75^th percentiles. If a box is not shown, that indicates the median, 25^th and/or 75^th percentile all had the same value.

Appendix Figure 7. CAM-S Scores by Costs Per Day (90 Day Follow-Up)

*Plots of maximal CAM-S scores per patient by costs per day. The green line runs through fitted values derived from log-gamma regression.

Appendix Figure 8. CAM-S Scores by Death or Nursing Home (NH) Residence at 90 Days*

* The maximal CAM-S score during each patient’s hospitalization was used in all analyses. Boxes around the plots represent the median, 25^th, and 75^th percentiles. If a box is not shown, that indicates the median, 25^th and/or 75^th percentile all had the same value.

Appendix Figure 9. CAM-S Scores by Functional Decline at 30 Days*

* The maximal CAM-S score during each patient’s hospitalization was used in all analyses. Functional decline was defined as a decline of 2 or more points of 14 points in activities of daily living between baseline and one-month follow-up scores (see text for details). Boxes around the plots represent the median, 25^th, and 75^th percentiles. If a box is not shown, that indicates the median, 25^th and/or 75^th percentile all had the same value.