The 4 ‘A’s test for detecting delirium in acute medical patients: a diagnostic accuracy study
Background: Delirium is a common and serious neuropsychiatric syndrome, usually triggered by illness or drugs. It remains underdetected. One reason for this is a lack of brief, pragmatic assessment tools. The 4 ‘A’s test (Arousal, Attention, Abbreviated Mental Test – 4, Acute change) (4AT) is a scre...
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NIHR Journals Library
2019-08-01
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Series: | Health Technology Assessment |
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Online Access: | https://doi.org/10.3310/hta23400 |
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doaj-b8957fe571df4354b049a2f59e6b82e5 |
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record_format |
Article |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Alasdair MJ MacLullich Susan D Shenkin Steve Goodacre Mary Godfrey Janet Hanley Antaine Stíobhairt Elizabeth Lavender Julia Boyd Jacqueline Stephen Christopher Weir Allan MacRaild Jill Steven Polly Black Katharina Diernberger Peter Hall Zoë Tieges Christopher Fox Atul Anand John Young Najma Siddiqi Alasdair Gray |
spellingShingle |
Alasdair MJ MacLullich Susan D Shenkin Steve Goodacre Mary Godfrey Janet Hanley Antaine Stíobhairt Elizabeth Lavender Julia Boyd Jacqueline Stephen Christopher Weir Allan MacRaild Jill Steven Polly Black Katharina Diernberger Peter Hall Zoë Tieges Christopher Fox Atul Anand John Young Najma Siddiqi Alasdair Gray The 4 ‘A’s test for detecting delirium in acute medical patients: a diagnostic accuracy study Health Technology Assessment DELIRIUM DEMENTIA ACUTE HOSPITALS 4AT DIAGNOSTIC ACCURACY CAM |
author_facet |
Alasdair MJ MacLullich Susan D Shenkin Steve Goodacre Mary Godfrey Janet Hanley Antaine Stíobhairt Elizabeth Lavender Julia Boyd Jacqueline Stephen Christopher Weir Allan MacRaild Jill Steven Polly Black Katharina Diernberger Peter Hall Zoë Tieges Christopher Fox Atul Anand John Young Najma Siddiqi Alasdair Gray |
author_sort |
Alasdair MJ MacLullich |
title |
The 4 ‘A’s test for detecting delirium in acute medical patients: a diagnostic accuracy study |
title_short |
The 4 ‘A’s test for detecting delirium in acute medical patients: a diagnostic accuracy study |
title_full |
The 4 ‘A’s test for detecting delirium in acute medical patients: a diagnostic accuracy study |
title_fullStr |
The 4 ‘A’s test for detecting delirium in acute medical patients: a diagnostic accuracy study |
title_full_unstemmed |
The 4 ‘A’s test for detecting delirium in acute medical patients: a diagnostic accuracy study |
title_sort |
4 ‘a’s test for detecting delirium in acute medical patients: a diagnostic accuracy study |
publisher |
NIHR Journals Library |
series |
Health Technology Assessment |
issn |
1366-5278 2046-4924 |
publishDate |
2019-08-01 |
description |
Background: Delirium is a common and serious neuropsychiatric syndrome, usually triggered by illness or drugs. It remains underdetected. One reason for this is a lack of brief, pragmatic assessment tools. The 4 ‘A’s test (Arousal, Attention, Abbreviated Mental Test – 4, Acute change) (4AT) is a screening tool designed for routine use. This project evaluated its usability, diagnostic accuracy and cost. Methods: Phase 1 – the usability of the 4AT in routine practice was measured with two surveys and two qualitative studies of health-care professionals, and a review of current clinical use of the 4AT as well as its presence in guidelines and reports. Phase 2 – the 4AT’s diagnostic accuracy was assessed in newly admitted acute medical patients aged ≥ 70 years. Its performance was compared with that of the Confusion Assessment Method (CAM; a longer screening tool). The performance of individual 4AT test items was related to cognitive status, length of stay, new institutionalisation, mortality at 12 weeks and outcomes. The method used was a prospective, double-blind diagnostic test accuracy study in emergency departments or in acute general medical wards in three UK sites. Each patient underwent a reference standard delirium assessment and was also randomised to receive an assessment with either the 4AT (n = 421) or the CAM (n = 420). A health economics analysis was also conducted. Results: Phase 1 found evidence that delirium awareness is increasing, but also that there is a need for education on delirium in general and on the 4AT in particular. Most users reported that the 4AT was useful, and it was in widespread use both in the UK and beyond. No changes to the 4AT were considered necessary. Phase 2 involved 785 individuals who had data for analysis; their mean age was 81.4 (standard deviation 6.4) years, 45% were male, 99% were white and 9% had a known dementia diagnosis. The 4AT (n = 392) had an area under the receiver operating characteristic curve of 0.90. A positive 4AT score (> 3) had a specificity of 95% [95% confidence interval (CI) 92% to 97%] and a sensitivity of 76% (95% CI 61% to 87%) for reference standard delirium. The CAM (n = 382) had a specificity of 100% (95% CI 98% to 100%) and a sensitivity of 40% (95% CI 26% to 57%) in the subset of participants whom it was possible to assess using this. Patients with positive 4AT scores had longer lengths of stay (median 5 days, interquartile range 2.0–14.0 days) than did those with negative 4AT scores (median 2 days, interquartile range 1.0–6.0 days), and they had a higher 12-week mortality rate (16.1% and 9.2%, respectively). The estimated 12-week costs of an initial inpatient stay for patients with delirium were more than double the costs of an inpatient stay for patients without delirium (e.g. in Scotland, £7559, 95% CI £7362 to £7755, vs. £4215, 95% CI £4175 to £4254). The estimated cost of false-positive cases was £4653, of false-negative cases was £8956, and of a missed diagnosis was £2067. Limitations: Patients were aged ≥ 70 years and were assessed soon after they were admitted, limiting generalisability. The treatment of patients in accordance with reference standard diagnosis limited the ability to assess comparative cost-effectiveness. Conclusions: These findings support the use of the 4AT as a rapid delirium assessment instrument. The 4AT has acceptable diagnostic accuracy for acute older patients aged > 70 years. Future work: Further research should address the real-world implementation of delirium assessment. The 4AT should be tested in other populations. Trial registration: Current Controlled Trials ISRCTN53388093. Funding: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 40. See the NIHR Journals Library website for further project information. The funder specified that any new delirium assessment tool should be compared against the CAM, but had no other role in the study design or conduct of the study. |
topic |
DELIRIUM DEMENTIA ACUTE HOSPITALS 4AT DIAGNOSTIC ACCURACY CAM |
url |
https://doi.org/10.3310/hta23400 |
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doaj-b8957fe571df4354b049a2f59e6b82e52020-11-25T01:57:18ZengNIHR Journals LibraryHealth Technology Assessment1366-52782046-49242019-08-01234010.3310/hta2340011/143/01The 4 ‘A’s test for detecting delirium in acute medical patients: a diagnostic accuracy studyAlasdair MJ MacLullich0Susan D Shenkin1Steve Goodacre2Mary Godfrey3Janet Hanley4Antaine Stíobhairt5Elizabeth Lavender6Julia Boyd7Jacqueline Stephen8Christopher Weir9Allan MacRaild10Jill Steven11Polly Black12Katharina Diernberger13Peter Hall14Zoë Tieges15Christopher Fox16Atul Anand17John Young18Najma Siddiqi19Alasdair Gray20Geriatric Medicine, Division of Health Sciences, University of Edinburgh, Edinburgh, UKGeriatric Medicine, Division of Health Sciences, University of Edinburgh, Edinburgh, UKEmergency Medicine, University of Sheffield, Sheffield, UKHealth and Social Care, Leeds Institute of Health Sciences, School of Medicine, Faculty of Medicine and Health, University of Leeds, Leeds, UKSchool of Health and Social Care, Edinburgh Napier University, Edinburgh, UKGeriatric Medicine, Division of Health Sciences, University of Edinburgh, Edinburgh, UKHealth and Social Care, Leeds Institute of Health Sciences, School of Medicine, Faculty of Medicine and Health, University of Leeds, Leeds, UKEdinburgh Clinical Trials Unit, University of Edinburgh, Edinburgh, UKEdinburgh Clinical Trials Unit, University of Edinburgh, Edinburgh, UKEdinburgh Clinical Trials Unit, University of Edinburgh, Edinburgh, UKEmergency Medicine Research Group (EMERGE), NHS Lothian, Edinburgh, UKEmergency Medicine Research Group (EMERGE), NHS Lothian, Edinburgh, UKEmergency Medicine Research Group (EMERGE), NHS Lothian, Edinburgh, UKUsher Institute of Population Health Sciences and Informatics, University of Edinburgh, Edinburgh, UKEdinburgh Clinical Trials Unit, University of Edinburgh, Edinburgh, UKGeriatric Medicine, Division of Health Sciences, University of Edinburgh, Edinburgh, UKNorwich Medical School, Faculty of Medicine and Health Sciences, University of East Anglia, Norwich, UKGeriatric Medicine, Division of Health Sciences, University of Edinburgh, Edinburgh, UKBradford Institute for Health Research, Bradford Royal Infirmary, Bradford, UKPsychiatry, University of York, YorkUsher Institute of Population Health Sciences and Informatics, University of Edinburgh, Edinburgh, UKBackground: Delirium is a common and serious neuropsychiatric syndrome, usually triggered by illness or drugs. It remains underdetected. One reason for this is a lack of brief, pragmatic assessment tools. The 4 ‘A’s test (Arousal, Attention, Abbreviated Mental Test – 4, Acute change) (4AT) is a screening tool designed for routine use. This project evaluated its usability, diagnostic accuracy and cost. Methods: Phase 1 – the usability of the 4AT in routine practice was measured with two surveys and two qualitative studies of health-care professionals, and a review of current clinical use of the 4AT as well as its presence in guidelines and reports. Phase 2 – the 4AT’s diagnostic accuracy was assessed in newly admitted acute medical patients aged ≥ 70 years. Its performance was compared with that of the Confusion Assessment Method (CAM; a longer screening tool). The performance of individual 4AT test items was related to cognitive status, length of stay, new institutionalisation, mortality at 12 weeks and outcomes. The method used was a prospective, double-blind diagnostic test accuracy study in emergency departments or in acute general medical wards in three UK sites. Each patient underwent a reference standard delirium assessment and was also randomised to receive an assessment with either the 4AT (n = 421) or the CAM (n = 420). A health economics analysis was also conducted. Results: Phase 1 found evidence that delirium awareness is increasing, but also that there is a need for education on delirium in general and on the 4AT in particular. Most users reported that the 4AT was useful, and it was in widespread use both in the UK and beyond. No changes to the 4AT were considered necessary. Phase 2 involved 785 individuals who had data for analysis; their mean age was 81.4 (standard deviation 6.4) years, 45% were male, 99% were white and 9% had a known dementia diagnosis. The 4AT (n = 392) had an area under the receiver operating characteristic curve of 0.90. A positive 4AT score (> 3) had a specificity of 95% [95% confidence interval (CI) 92% to 97%] and a sensitivity of 76% (95% CI 61% to 87%) for reference standard delirium. The CAM (n = 382) had a specificity of 100% (95% CI 98% to 100%) and a sensitivity of 40% (95% CI 26% to 57%) in the subset of participants whom it was possible to assess using this. Patients with positive 4AT scores had longer lengths of stay (median 5 days, interquartile range 2.0–14.0 days) than did those with negative 4AT scores (median 2 days, interquartile range 1.0–6.0 days), and they had a higher 12-week mortality rate (16.1% and 9.2%, respectively). The estimated 12-week costs of an initial inpatient stay for patients with delirium were more than double the costs of an inpatient stay for patients without delirium (e.g. in Scotland, £7559, 95% CI £7362 to £7755, vs. £4215, 95% CI £4175 to £4254). The estimated cost of false-positive cases was £4653, of false-negative cases was £8956, and of a missed diagnosis was £2067. Limitations: Patients were aged ≥ 70 years and were assessed soon after they were admitted, limiting generalisability. The treatment of patients in accordance with reference standard diagnosis limited the ability to assess comparative cost-effectiveness. Conclusions: These findings support the use of the 4AT as a rapid delirium assessment instrument. The 4AT has acceptable diagnostic accuracy for acute older patients aged > 70 years. Future work: Further research should address the real-world implementation of delirium assessment. The 4AT should be tested in other populations. Trial registration: Current Controlled Trials ISRCTN53388093. Funding: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 40. See the NIHR Journals Library website for further project information. The funder specified that any new delirium assessment tool should be compared against the CAM, but had no other role in the study design or conduct of the study.https://doi.org/10.3310/hta23400DELIRIUMDEMENTIAACUTE HOSPITALS4ATDIAGNOSTIC ACCURACYCAM |