Cognitive Trajectories after Postoperative Delirium

Meredith Cook PharmD CandidateMercer University COPHSAugust, 2012Cognitive Trajectories after Postoperative Delirium

RelevanceMany patients do not return to their preoperative level of cognition within 3 months of cardiac surgery.Risk factorsOlder age, lower education level, presence of 1 or more coexisting conditionsDelirium affects up to of patients following cardiac surgeryAssociated with adverse outcomes (functional decline, increased healthcare costs, and/or death)

Rationale/MethodsConducted by Saczynski, J.S., et al. at two academic medical centers and one VA hospitalInclusion criteria: 60 years of age or older who were planning to undergo CABG or valve replacementPatients follow up to 1 year post-opFunded by: Harvard Older Americans Independence Center and othersRationale/MethodsPreoperative AssessmentDemographics, behavioral factors, functional ability (Katz Index of Independence in ADLs) coexisting conditions, and cognitive function (MMSE)Postoperative AssessmentBegan on post-op day 2 and continuing daily until discharge (MMSE, digit-span test, CAM, and Delirium Symptom Interview)After discharge, patients were interviewed in person at 1, 6, and 12 months

Katz scores range from 0 (complete DEPENDENCE) to 12 (complete INDEPENDENCE)CAM Confusion Assessment Method diagnostic algorithm to determine the presence or absence of delirium on the basis of four features: acute change with a fluctuating course, inattention, disorganized thinking, and altered level of consciousness) This test has a high sensitivity (94%) and high specificity (98%) for ratings of delirium in geriatric psychiatrists.Delirium Symptom Interview assesses presence or absence of 8 features of delirium, including the 4 features of CAM

If a patient was intubated, then assessment for delirium was performed with the use of the CAM for ICU (a validated nonverbal version of the CAM)

Combined assessment for delirium was highly reliable (kappa=0.95)4Rationale/Methods24.4% of the daily delirium assessments were missing (due to staff or patient unavailability ie: weekend staffing)The missing assessments did not differ significantly between patients who had delirium and those who did notAll patients underwent at least 1 delirium assessment on post-op day 2 or 3Charlson co-morbidity index was also calculatedCharlson co-morbidity index a weighted sum of 17 medical conditions (with higher scores indicating a greater burden of illness)5Statistical AnalysisBaseline characteristics chi-square test for categorical variables and analysis of variance for continuous variablesMMSE scores over time hierarchical linear regression modelMMSE scores were adjusted for age, educational level, sex, race/ethnic group, score on Charlson comorbidity index, presence or absence of stroke or TIA, surgery type, and hospitalStatistical AnalysisSensitivity AnalysesBaseline differences in MMSE scores according to delirium statusDuration of deliriumExcluded 7 patients who had a stroke postoperatively

Results225 patientsAverage age: 73 +6.7 (range: 60-90) femaleMost were white, non-Hispanic

ResultsPostoperative delirium developed in 46% of patientsLasted 1-2 days in 65%; 3 or more days in 35%Delirium patients were significantly older, less educated, more likely to be women, and less likely to be whiteAlso more likely to have a history of stroke or TIA and a higher average score on the Charlson co-morbidity index and lower level of preoperative cognitive functionResults: Cognitive Function ScoresAvg. MMSE before surgery: 26.9Postoperative day 2: -4.6 points (p