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Validation of the confusion assessment method in detecting postoperative delirium in cardiac surgery patients
Umeå University, Faculty of Medicine, Department of Nursing. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery. (Cardiothoracic Surgery Division)
Umeå University, Faculty of Medicine, Department of Nursing. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences. (Cardiothoracic Surgery Division; Heart Centre)
Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Geriatric Medicine.
Umeå University, Faculty of Medicine, Department of Nursing. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Orthopaedics.
Show others and affiliations
2015 (English)In: American Journal of Critical Care, ISSN 1062-3264, E-ISSN 1937-710X, Vol. 24, no 6, p. 480-487Article in journal (Refereed) Published
Abstract [en]

Background: Early detection, prevention, and treatment of delirium after cardiac surgery are important for quick postoperative recovery. The Confusion Assessment Method (CAM) may be an easy-to-use instrument for detecting delirium in clinical practice.

Objectives: To compare the congruent validity of the CAM with the results from repeated assessments by using a combination of the Organic Brain Syndrome Scale and the Mini-Mental State Examination according to the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition, Text Revision) criteria for delirium.

Methods: Patients aged 70 years or older undergoing cardiac surgery were assessed on postoperative days 1 and 4, and the 2 diagnostic methods were compared. The sensitivity and specificity of the CAM were examined. The reference method allowed categorization of delirium into subgroups of psychomotor activities and psychiatric symptom profiles, which were compared with the CAM results.

Results: Postoperative delirium was diagnosed in 78 of 141 patients (55.3%). According to the CAM, 59 patients (41.8%) were categorized as delirious, 53 correctly. Thus, the sensitivity was 68% and the specificity was 90%, indicating false-negative rather than false-positive observations.

Conclusion: Patients with psychomotor hyperactivity and mixed psychotic-emotional symptoms were more likely to have delirium detected via the CAM than were patients with less obvious clinical manifestations of delirium. Repetitive cognitive testing and psychogeriatric experience are probably necessary to improve the results obtained with the CAM.

Place, publisher, year, edition, pages
American Association of Critical-Care Nurses , 2015. Vol. 24, no 6, p. 480-487
Keywords [en]
mini-mental state, risk factors, hospital patients, elderly patients, older people, 3 scores, intervention, fracture, profile, screen
National Category
Nursing Surgery Cardiac and Cardiovascular Systems
Identifiers
URN: urn:nbn:se:umu:diva-111993DOI: 10.4037/ajcc2015551ISI: 000364316700004PubMedID: 26523005Scopus ID: 2-s2.0-84948763767OAI: oai:DiVA.org:umu-111993DiVA, id: diva2:876456
Available from: 2015-12-03 Created: 2015-11-30 Last updated: 2023-03-24Bibliographically approved
In thesis
1. Delirium after cardiac surgery: risk factors, assessment methods and costs
Open this publication in new window or tab >>Delirium after cardiac surgery: risk factors, assessment methods and costs
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: Cardiac surgery is considered safe, but postoperative delirium (POD) remains frequently reported. Delirium is characterised by fluctuations in consciousness and cognition, and can be subdivided into disturbed psychomotoric activity (hyperactive and hypoactive) and psychiatric symptom profiles (psychotic and emotional). Delirium has an underlying cause that can be prevented and treated, provided the condition is detected. Undetected delirium could lead to serious consequences for the patient.

Aim: This thesis aims to understand the underlying risk factors of delirium, to compare different assessment methods and documentation, and to understand its effects on hospitalisation costs after cardiac surgery.

Methods: Two cohorts of patients undergoing cardiac surgery at the Heart Centre, Umeå University Hospital, Sweden were analysed. Cohort-A (Studies I-IV) enrolled 142 patients, ≥70 years of age, scheduled in 2009 for surgery with cardiopulmonary bypass (CPB). POD was diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders 4th ed, text rev (DSM-IV-TR), based on repetitive assessments with the Mini-Mental State Examination (MMSE) and the Organic Brain Syndrome (OBS) scale. This method was considered as reference. Predisposing and precipitating risk factors were explored (Study I), and a separate analysis was conducted with focus on CPB parameters (Study II). Patients were also assessed for POD with the Confusion Assessment Method (CAM), which was validated versus the reference method (Study III). Additionally in Study IV, data about how nurses assessed patients for POD symptoms using the Nursing Delirium Screening Scale (Nu-DESC) were analysed together with information extracted from the clinical database. Moreover, discharge summaries from both nurses and physicians were retrospectively reviewed for key words and expression associated with delirium. Cohort-B (Study V) included 1879 routine cardiac surgery patients (2014-2017) retrospectively extracted from the clinical database with concomitant Nu-DESC scoring. The association between the Nu-DESC and postoperative hospitalization costs was analysed.

Results: In cohort-A, 54.9% (78/142) patients developed POD. Both predisposing and precipitating risk factors were significantly associated with POD, of which the ‘volume load during operation’ had the strongest predictive influence (Study I). Among CPB variables the ‘duration of mixed-venous oxygen saturation <75%’ predicted POD (Study II). Hypoactive was more common than hyperactive delirium. Those with hypoactive delirium were less likely to be detected by the CAM method (Study III), an observation also demonstrated from information found in the clinical database and in discharge summaries. Nu-DESC did not detect all patients with POD, but significantly increased the detection rate (Study IV). The major hospitalisation costs associated with Nu-DESC ≥2 occurred in the ICU and independently of the surgical procedure performed. There were no significant differences in costs among patients with Nu-DESC ≥2, between age groups (70-year cut-off) or genders (Study V).

Conclusions: Both predisposing and precipitating risk factors contributed to POD and should be considered in future guidelines to prevent delirium after cardiac surgery. Hypoactive delirium was most common, but was the most difficult to detect without screening scales. Systematic assessment with Nu-DESC improved the detection rate of POD. Delirium after cardiac surgery has consequences on healthcare and is associated with increased costs.

Abstract [sv]

Bakgrund: Hjärtkirurgi anses idag vara en säker metod men det förkommer frekventa rapporter om postoperativt delirium (POD). Delirium kännetecknas av fluktuationer i medvetandet och kognition och kan delas in i störd psykomotorisk aktivitet (hyperaktiva och hypoaktiva) och psykiatriska symtomprofiler (psykotiska och emotionella). Delirium har underliggande orsaker som kan förebyggas och behandlas, förutsatt att tillståndet upptäcks. Ett oupptäckt delirium kan leda till allvarliga konsekvenser för patienten.

Syfte: Denna avhandling syftar till att förstå de underliggande riskfaktorerna för delirium, jämföra olika bedömningsmetoder och dokumentation samt förstå effekterna på vårdkostnaderna efter hjärtkirurgi.

Metod: Två kohorter av patienter som genomgått hjärtkirurgi vid Hjärtcentrum, Umeå Universitetssjukhus, Sverige analyserades. I kohort-A (Studie I-IV) inkluderades 142 patienter, ≥70 år planerade för operation med hjärt-lungmaskin under 2009. POD diagnostiserades enligt Diagnostic and Statistical Manual of Mental Disorders 4th ed, text rev (DSM-IV-TR), baserat på upprepade skattningar med Mini Mental State Examination (MMSE) och Organic Brain Syndrom(OBS) scale. Denna metod betraktas som referens. Predisponerande och utlösande riskfaktorer analyserades (Studie I), och en separat analys genomfördes med fokus på hjärt-lungmaskinens parametrar (Studie II). Patienterna bedömdes också för POD med Confusion Assessment Method (CAM), vilken validerades mot referensmetoden (Studie III). Vidare analyserades uppgifter om hur sjuksköterskor skattade patienterna för POD symtom med Nursing Delirium Screening Scale (Nu-DESC) tillsammans med information hämtad från den kliniska databasen. Dessutom granskades både sjuksköterskornas och läkarnas epikriser retrospektivt för nyckelord och uttryck associerade med delirium. Kohort-B (Studie V) inkluderade 1879 rutinmässiga hjärtkirurgiska patienter (2014-2017) som extraherades retrospektivt från den kliniska databasen med samtidiga Nu-DESC-poäng. Sambandet mellan Nu-DESC och de postoperativa vårdkostnaderna analyserades.

Resultat: I kohort-A, utvecklade 54,9% (78/142) av patienterna POD. Både predisponerande och utlösande riskfaktorer var signifikant associerade med POD, varav ’volymbelastningen under operation’ hade det starkaste prediktiva inflytandet (Studie I). Bland hjärt-lungmaskinens variabler bidrog ’duration av blandad venös syremättnad <75%’ till POD (Studie II). Hypoaktivt delirium var vanligare än hyperaktivt. Patienter med hypoaktiv delirium upptäcktes i mindre utsträckning med CAM (Studie III), en observation som också visade sig i information från den kliniska databasen och i epikriserna. Nu-DESC upptäckte inte alla patienter med POD men ökade detekteringsgraden signifikant (Studie IV). De största vårdkostnaderna i samband med Nu-DESC-poäng ≥2 inträffade på intensivvårdsavdelningen oberoende av kirurgiskt ingrepp som utförts. Det fanns inga signifikanta skillnader i kostnaderna mellan åldersgrupper (70-års brytpunkt) eller mellan män och kvinnor med Nu-DESC ≥2 (Studie V).

Slutsatser: Både predisponerande och utlösande riskfaktorer bidrar till POD och bör övervägas i framtida riktlinjer för att förhindra delirium efter hjärtkirurgi. Hypoaktivt delirium var vanligast men också svåraste att upptäcka utan bedömningsskalor. Systematisk bedömning med Nu-DESC förbättrade upptäckten av POD. Delirium efter hjärtkirurgi har konsekvenser för vården och är förknippad med ökade kostnader.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2018. p. 55
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1967
Keywords
Cardiac surgery, Cardiopulmonary bypass, Consequences, Delirium, Detection, Documentation, Economical aspect, Hospitalisation, Risk factors, Screening scales
National Category
Surgery Nursing
Research subject
Thoracic and Cardivascular Suregery; Caring Sciences
Identifiers
urn:nbn:se:umu:diva-151414 (URN)978-91-7601-909-2 (ISBN)
Public defence
2018-09-28, Aulan, Vårdvetarhuset, Umeå, 09:00 (Swedish)
Opponent
Supervisors
Available from: 2018-09-07 Created: 2018-09-03 Last updated: 2023-04-26Bibliographically approved

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Smulter, NinaClaesson Lingehall, HelenaGustafson, YngveOlofsson, BirgittaEngström, Karl Gunnar

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