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Clarifying Confusion: The Confusion Assessment Method
Sharon K. Inouye, Christopher H. van Dyck, Cathy Alessi, Sharyl Balkin, Alan P. Siegal, Ralph I. Horwitz. Annals of Internal Medicine, 1990-12-15
Topic: Risk, prevention and care in population studies
OBJECTIVE: To develop and validate a new standardized confusion assessment method (CAM) that enables nonpsychiatric clinicians to detect delirium quickly in high-risk settings. DESIGN: Prospective validation study. SETTING: Conducted in general medicine wards and in an outpatient geriatric assessment center at Yale University (site 1) and in general medicine wards at the University of Chicago (site 2). PATIENTS: The study included 56 subjects, ranging in age from 65 to 98 years. At site 1, 10 patients with and 20 without delirium participated; at site 2, 16 patients with and 10 without delirium participated. MEASUREMENTS AND MAIN RESULTS: An expert panel developed the CAM through a consensus building process. The CAM instrument, which can be completed in less than 5 minutes, consists of nine operationalized criteria from the Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R). An a priori hypothesis was established for the diagnostic value of four criteria: acute onset and fluctuating course, inattention, disorganized thinking, and altered level of consciousness. The CAM algorithm for diagnosis of delirium required the presence of both the first and the second criteria and of either the third or the fourth criterion. At both sites, the diagnoses made by the CAM were concurrently validated against the diagnoses made by psychiatrists. At sites 1 and 2 values for sensitivity were 100% and 94%, respectively; values for specificity were 95% and 90%; values for positive predictive accuracy were 91% and 94%; and values for negative predictive accuracy were 100% and 90%. The CAM algorithm had the highest predictive accuracy for all possible combinations of the nine features of delirium. The CAM was shown to have convergent agreement with four other mental status tests, including the Mini-Mental State Examination. The interobserver reliability of the CAM was high (kappa = 0.81 - 1.0). CONCLUSIONS: The CAM is sensitive, specific, reliable, and easy to use for identification of delirium.
Why it matters
This study developed and tested the Confusion Assessment Method (CAM), a tool that lets clinicians who are not psychiatrists detect delirium quickly. It can be completed in less than 5 minutes, and when checked against psychiatrists' diagnoses in 56 older patients at both study sites, the authors found it sensitive, specific, reliable and easy to use.
How this study scored 51/100
Published in a leading specialty journal. Scored zero for study design, sample size, effect reported, studied in people and randomised / blinded because the record does not state it. We have no data on strength of evidence and senior author's track record, so those were left out: it earned 46 of the 91 points we could judge it on, which is 51 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 9 / 10 | Tier 2 — leading specialty journal (Annals of Internal Medicine) |
| Journal's citation record | 4 / 4 | Annals of Internal Medicine: journal h-index 648 (OpenAlex, 2026-10-29) |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | — / 5 | No evidence rating recorded — left out of this score |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 1 / 5 | 1990 — older than 20 years, still counted |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | 7 / 7 | Cited 5,262 times (OpenAlex, 2026-10-10) |
| Citations per year | 5 / 5 | 138.5 citations a year over 38 year(s) since 1990 |
| Impact for its field and year | 3 / 6 | Cited 7.6× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 0 / 6 | No other study in this library cites it |
| Still being cited | 4 / 4 | Cited 709 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | — / 4 | Senior author's record not available — left out of this score |
| Institution's track record | 2 / 3 | Yale University: institution h-index 1,927 (OpenAlex) |
| Multi-centre collaboration | 0 / 3 | OpenAlex lists 1 institution(s) in 1 country — scores zero (affiliation lists can be incomplete) |
| Indexed in PubMed | 1 / 2 | Not in PubMed, but has a DOI |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Points | 46 / 91 | Scored on 18 of 20 parts. We have no data for the rest, so they are left out: 46 of the 91 points we could judge it on is 51 out of 100. |
| Total | 51 / 100 | — |
What each of these 20 components measures, and what this score is not →
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Cite this study APA, Vancouver, BibTeX · download .bib or .ris
Built from the record alzhub holds for this paper, not looked up. Volume, issue and page numbers are not held in the record. Check the citation against the original before you use it.
APA 7th
Inouye, S. K., van Dyck, C. H., Alessi, C., Balkin, S., Siegal, A. P., & Horwitz, R. I. (1990). Clarifying Confusion: The Confusion Assessment Method. Annals of Internal Medicine. https://doi.org/10.7326/0003-4819-113-12-941
Vancouver
Inouye SK, van Dyck CH, Alessi C, Balkin S, Siegal AP, Horwitz RI. Clarifying Confusion: The Confusion Assessment Method. Annals of Internal Medicine. 1990. doi:10.7326/0003-4819-113-12-941.
BibTeX
@article{inouye1990-bf9d2bc3,
author = {Inouye, Sharon K. and van Dyck, Christopher H. and Alessi, Cathy and Balkin, Sharyl and Siegal, Alan P. and Horwitz, Ralph I.},
title = {{Clarifying Confusion: The Confusion Assessment Method}},
journal = {Annals of Internal Medicine},
year = {1990},
doi = {10.7326/0003-4819-113-12-941},
url = {https://doi.org/10.7326/0003-4819-113-12-941}
}