Meredith Cook – PharmD Candidate Mercer University COPHS August, 2012 Cognitive Trajectories after Postoperative Delirium

Relevance Many patients do not return to their preoperative level of cognition within 3 months of cardiac surgery. Risk factors Older age, lower education level, presence of 1 or more coexisting conditions Delirium affects up to ¾ of patients following cardiac surgery Associated with adverse outcomes (functional decline, increased healthcare costs, and/or death)

Rationale/Methods Conducted by Saczynski, J.S., et al. at two academic medical centers and one VA hospital Inclusion criteria: 60 years of age or older who were planning to undergo CABG or valve replacement Patients follow up to 1 year post-op Funded by: Harvard Older Americans Independence Center and others

Rationale/Methods Preoperative Assessment Demographics, behavioral factors, functional ability (Katz Index of Independence in ADLs) coexisting conditions, and cognitive function (MMSE) Postoperative Assessment Began 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

Rationale/Methods 24.4% 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 not All patients underwent at least 1 delirium assessment on post-op day 2 or 3 Charlson co-morbidity index was also calculated

Statistical Analysis Baseline characteristics – chi-square test for categorical variables and analysis of variance for continuous variables MMSE scores over time – hierarchical linear regression model MMSE 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 hospital

Statistical Analysis Sensitivity Analyses Baseline differences in MMSE scores according to delirium status Duration of delirium Excluded 7 patients who had a stroke postoperatively

Results 225 patients Average age: (range: 60-90) ¼ female Most were white, non-Hispanic

Results Postoperative delirium developed in 46% of patients Lasted 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 white Also 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 function

Results: Cognitive Function Scores Avg. MMSE before surgery: 26.9 Postoperative day 2: -4.6 points (p<0.001) Postoperative days 3-5: +1 point (p<0.001) Improvement slowed considerably from day 6 – day 183 No significant improvement from day 183 – day 365

Results: Cognitive Trajectories According To Delirium Status Post-op delirium patients had significantly lower MMSE scores pre-operatively than those without delirium (25.8 vs. 26.9, p<0.001) Greater decline in cognitive function immediately following surgery in those who developed delirium (-7.7 points vs points, p<0.001)

Results: Cognitive Trajectories According To Delirium Status No delirium – returned to baseline ~1 month postoperatively With delirium – had NOT returned to baseline by 1 year postoperatively

Sensitivity Analysis Longer duration of delirium was associated with a more significant drop in MMSE score immediately following surgery and slower recovery in the 1 year post-op period (> 3 days vs. < 3 days) These results were similar when patients were excluded who had a stroke post-op and when MMSE scores were ranked to address non-normal distribution (no data was given in the study)

Discussion Delirium after cardiac surgery is associated with an initial decline in cognitive function, followed by an extended period of impairment After MMSE adjustment for baseline characteristics, the average MMSE scores did not differ significantly in patients with and those without delirium at 6 months and 1 year post- op

Discussion Delirium may have long-term effects on cognitive function following cardiac surgery Post-op delirium associated with prolonged cognitive dysfunction? Clinically significant – risk of delirium can be predicted pre- op (delirium is preventable)

My Conclusions Does risk outweigh benefits? Educate patients on possible risk of decline in cognitive function Thoroughly test before surgery to assess pre-op cognitive abilities Identify high-risk patients

References Saczynksi, Jane S. Cognitive Trajectories after Postoeprative Delirium. NEJM. July 5, 2012; 367:30-9.