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Original Research |

The CAM-S: Development and Validation of a New Scoring System for Delirium Severity in 2 CohortsThe CAM-S Score for Delirium Severity

Sharon K. Inouye, MD, MPH; Cyrus M. Kosar, MA; Douglas Tommet, MS, MPH; Eva M. Schmitt, PhD; Margaret R. Puelle, BS; Jane S. Saczynski, PhD; Edward R. Marcantonio, MD, SM*; and Richard N. Jones, ScD*
[+] Article and Author Information

* Drs. Marcantonio and Jones contributed equally as co–senior authors.


From Beth Israel Deaconess Medical Center, Harvard Medical School, and Hebrew SeniorLife, Boston, Massachusetts; University of Massachusetts Medical School, Worcester, Massachusetts; and Warren Alpert Medical School of Brown University, Providence, Rhode Island.

Note: The CAM algorithm and instrument are copyrighted to the Hospital Elder Life Program, LLC (www.hospitalelderlifeprogram.org). Instructions and training manual are available at the Web site.

Acknowledgment: The authors thank the patients, families, physicians, and research staff who participated in the SAGES and Project Recovery studies and made this study possible. This work is dedicated to the memory of Joshua Bryan Inouye Helfand and Bradley Yoshio Inouye.

Grant Support: By National Institute on Aging grants P01AG031720 and K07AG041835 (Dr. Inouye), R01AG030618 and K24AG035075 (Dr. Marcantonio), and K01AG033643 (Dr. Saczynski). Dr. Inouye holds the Milton and Shirley F. Levy Family Chair.

Disclosures: None. Forms can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M13-1927.

Reproducible Research Statement: Study protocol, statistical code, and data set: Available on request from Dr. Inouye (e-mail, AgingBrainCenter@hsl.harvard.edu).

Requests for Single Reprints: Sharon K. Inouye, MD, MPH, Aging Brain Center, Institute for Aging Research, Hebrew SeniorLife, 1200 Centre Street, Boston, MA 02459; e-mail, AgingBrainCenter@hsl.harvard.edu.

Current Author Addresses: Drs. Inouye and Schmitt, Mr. Kosar, and Ms. Puelle: Aging Brain Center, Institute for Aging Research, Hebrew SeniorLife, 1200 Centre Street, Boston, MA 02131.

Mr. Tommet: Butler Hospital, Duncan Building, 700 Butler Drive, Providence, RI 02912.

Dr. Saczynski: University of Massachusetts Medical School, Division of Geriatric Medicine, 377 Plantation Street, Biotech 4, Suite 315, Worcester, MA 01655.

Dr. Marcantonio: Harvard Medical School, Division of General Medicine and Primary Care, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215.

Dr. Jones: Butler Hospital, 345 Blackstone Boulevard, Providence, RI 02906.

Author Contributions:Conception and design: S.K. Inouye, E.R. Marcantonio, R.N. Jones.

Analysis and interpretation of the data: S.K. Inouye, C.M. Kosar, D. Tommet, E.R. Marcantonio, R.N. Jones.

Drafting of the article: S.K. Inouye.

Critical revision of the article for important intellectual content: S.K. Inouye, C.M. Kosar, E.M. Schmitt, M.R. Puelle, J.S. Saczynski, E.R. Marcantonio, R.N. Jones.

Final approval of the article: S.K. Inouye, C.M. Kosar, E.M. Schmitt, M.R. Puelle, J.S. Saczynski, E.R. Marcantonio, R.N. Jones.

Provision of study materials or patients: S.K. Inouye, E.R. Marcantonio.

Statistical expertise: S.K. Inouye, C.M. Kosar, D. Tommet, E.R. Marcantonio, R.N. Jones.

Obtaining of funding: S.K. Inouye, E.R. Marcantonio.

Administrative, technical, or logistic support: S.K. Inouye, C.M. Kosar, E.M. Schmitt, M.R. Puelle.

Collection and assembly of data: S.K. Inouye, C.M. Kosar, D. Tommet, E.M. Schmitt, E.R. Marcantonio.


Ann Intern Med. 2014;160(8):526-533. doi:10.7326/M13-1927
Text Size: A A A

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

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Appendix Figure 1.

CAM-S scores, by length of stay.

Plots are of maximum scores per patient by length of hospital stay. The green line runs through fitted values derived from log-γ regression.

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Grahic Jump Location
Appendix Figure 2.

CAM-S scores, by hospital costs.

Plots are of maximum scores per patient by hospital costs. The green line runs through fitted values derived from log-γ regression.

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Grahic Jump Location
Appendix Figure 3.

CAM-S scores, by new nursing home placement.

The maximum score during each patient's hospitalization was used in all analyses. Boxes around the plots represent the median and 25th and 75th percentiles. If a box is not shown, the median and 25th or 75th percentiles had the same value.

Grahic Jump Location
Grahic Jump Location
Appendix Figure 4.

CAM-S scores, by functional decline.

The maximum score during each patient's hospitalization was used in all analyses. Functional decline was defined as a partial or complete decline in ≥1 activity on the standard 7-item Activities of Daily Living scale between baseline and discharge (see text for details). Boxes around the plots represent the median and 25th and 75th percentiles. If a box is not shown, the median and 25th or 75th percentiles had the same value.

Grahic Jump Location
Grahic Jump Location
Appendix Figure 5.

CAM-S scores, by cognitive decline.

The maximum score during each patient's hospitalization was used in all analyses. Cognitive decline was defined as a decrease of ≥2 points in the Mini-Mental State Examination score between baseline and discharge. Boxes around the plots represent the median and 25th and 75th percentiles. If a box is not shown, the median and 25th or 75th percentiles had the same value.

Grahic Jump Location
Grahic Jump Location
Appendix Figure 6.

CAM-S scores, by death within 90 d.

The maximum score during each patient's hospitalization was used in all analyses. Boxes around the plots represent the median and 25th and 75th percentiles. If a box is not shown, the median and 25th or 75th percentiles had the same value.

Grahic Jump Location
Grahic Jump Location
Appendix Figure 7.

CAM-S scores, by cost per day for the first 90 d.

Plots are of maximum scores per patient by cost per day. The green line runs through fitted values derived from log-γ regression. For 14 patients, the observed values were <0 log dollars. The values were 0.10 to 0.98 dollars per day (−2.30 to −0.018 log dollars per day).

Grahic Jump Location
Grahic Jump Location
Appendix Figure 8.

CAM-S scores, by death or nursing home residence at 90 d.

The maximum score during each patient's hospitalization was used in all analyses. Boxes around the plots represent the median and 25th and 75th percentiles. If a box is not shown, the median and 25th or 75th percentiles had the same value.

Grahic Jump Location
Grahic Jump Location
Appendix Figure 9.

CAM-S scores, by functional decline at 30 d.

The maximum score during each patient's hospitalization was used in all analyses. Functional decline was defined as a partial or complete decline in ≥1 activity on the standard 7-item Activities of Daily Living scale between baseline and 1-mo follow-up (see text for details). Boxes around the plots represent the median and 25th and 75th percentiles. If a box is not shown, the median and 25th or 75th percentiles had the same value.

Grahic Jump Location
Grahic Jump Location
Figure.

Distribution of CAM-S scores, by delirium status in total sample and stratified by dementia status.

The maximum score during each patient's hospitalization was used in all analyses. Boxes around the plots represent the median and 25th and 75th percentiles. If a box is not shown, the median and 25th or 75th percentiles had the same value. The stratified analyses by dementia group were conducted in the Project Recovery sample. SAGES = Successful Aging After Elective Surgery.

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The CAM-S for Delirium versus New Gold Standard of Rapid High Amplitude Critical Reversible Cognitive Decline
Posted on May 4, 2014
Paul Regal FRACP FRCP
Senior Lecturer in Geriatric Medicine, University of Newcastle, Australia
Conflict of Interest: None Declared
Inouye [1] extended the 24-year old Confusion Assessment Method [2] (CAM) from dichotomy to the interval CAM-S. Neither qualifies as a gold standard. I offer 13 reasons for switching from CAM to a genuine gold standard: 1) A mathematician would divide cognitive decline into slow non-reversible cognitive decline (SNRCD / dementia) and rapid reversible CD (five phenotypes by cognitive domain); 2) The logical gold standard for RRCD of attention/executive function/memory (delirium) is rapid high amplitude critical reversible decline (RHACRCD): 25% / 24 hours. This greatly exceeds daily variability. RHACRCD is 2,300 fold faster than Alzheimer disease (4% per year); 3) 126 subjects in my prospective randomized controlled delirium trial (CADIS Clinical Trials.Gov NCT01650896) demonstrated 72% decline in executive function by selective instrumental activities of daily living (SIADL) over 24 hours from onset. Attention by 5-digit span forward (5-DSF) fell 33% and 6-DSF 53% [3]; 4) Speed and amplitude of recovery is the secondary gold standard distinguishing delirium from dementia. 90% of CADIS patients recovered 5-DSF within 7 days, 77% 6-DSF and 53% Delirium Index [4] (DI). Mean day to resolution was 1.95 for 5-DSF, 5.56 for 6-DSF and 7.82 for DI; 5) A study of 647 acute geriatric admissions in 2011-2012 [5] showed CAM positivity did not predict survival and only predicted nursing home placement in univariate analysis, contradicting Inouye’s [1] 1995-1998 data. 6) The 1990 CAM-4 and the new CAM-S-4 share weaknesses #6-9 [6]: Acute onset occurs frequently in behavioural and psychological symptoms of dementia (BPSD) and psychosis without cognitive decline as in Parkinson’s disease; 7) Fluctuation can occur for a myriad reasons such as sleep deprivation and diffuse Lewy body dementia; 8) The CAM inattention criteria does not mandate new or worsened inattention – 6-DSF is usually impaired in dementia; 9) Disorganized thinking is routine in dementia and detecting worsening in disorganized thinking is subjective. 10) The long-form CAM and CAM-S-10 share additional weaknesses #10-12: disorientation is common in dementia; 11) memory impairment is common in dementia; 12) altered sleep wake cycle occurs in non-delirious hospital inpatients due to procedures disrupting sleep. 13) Inouye [1] claims poor outcome with higher CAM-S based solely on 919 admissions in 1995-1998, contrasting with favourable outcomes in my 647 admissions in 2011-2012 [5]. 14) The large number of CAM publications reflects bias and ridicule against new methods such as RHACRCD rather than endorsement of CAM; 15) What IADL instrument appeared in Table 1?
References:
1. Inouye SK, Kosar CM, Tommet D et al. The CAM-S: development and validation of a new scoring system for delirium severity in 2 cohorts. Ann Intern Med. 2014;160:526-533.
2. Inouye SK, van Dyck CH, Alessi CA, Balkin S, Siegal AP, Horwitz RI. Clarifying confusion: The confusion assessment method. A new method for detection of delirium. Ann Intern Med. 1990;113:941-48.
3. Regal P. Delirium Reversibility and Instrumental Activities of Daily Living (IADL). Geriatrics and Gerontology International. 2014;14:in press
4. McCusker J, Cole M, Bellavance F, et al. The reliability and validity of a new measure of severity of delirium. International Psychogeriatrics. 1998;10:421-433.
5. Regal P. Confusion Assessment Method (CAM) indicators when CAM positivity in 647 patients has good outcome. J Am Ger Soc. 2013;61:173.
6. Regal P. Improving the logic and rigor of delirium trials. Internal Medicine Journal. 2013;43:1260.
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