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.

Figures

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, 25th, and 75th percentiles. If a box is not shown, that indicates the median, 25th and 75th 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, 25th, and 75th percentiles. If a box is not shown, that indicates the median, 25th and/or 75th 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, 25th, and 75th percentiles. If a box is not shown, that indicates the median, 25th and/or 75th 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, 25th, and 75th percentiles. If a box is not shown, that indicates the median, 25th and/or 75th 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, 25th, and 75th percentiles. If a box is not shown, that indicates the median, 25th and/or 75th 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, 25th, and 75th percentiles. If a box is not shown, that indicates the median, 25th and/or 75th 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, 25th, and 75th percentiles. If a box is not shown, that indicates the median, 25th and/or 75th percentile all had the same value.