Austin CA, et al. - In this prospective cohort study, researchers investigated if postoperative delirium is associated with decreased long-term cognition in a heterogeneous adult population. Outcomes revealed no statistically significant association between 90-day cognition and postoperative delirium, however, patients with preoperative cognitive impairment seem to have improvements in cognition 90 days after surgery, but this improvement may be reduced if they become delirious.

Methods

• From September 5, 2017 through January 15, 2018, researchers performed a prospective cohort study at a single academic medical center (≥800 beds) in the southeastern US.
• Patients aged 18 years or older who were English-speaking and were anticipated to require at least 1 night of hospital admission after a scheduled major nonemergent surgery were eligible for the study; they excluded prisoners, individuals without baseline cognitive assessments, and those who could not provide informed consent.
• They performed 90-day follow-up assessments on 135 patients (70.7%).
• Postoperative delirium defined as any instance of delirium occurring 24 to 72 hours after an operation, was the primary exposure.
• The research team diagnosed delirium using the Confusion Assessment Method (CAM).
• Change in cognition at 90 days after surgery compared with baseline, preoperative cognition was assessed as the primary outcome.
• They used a telephone version of the Montreal Cognitive Assessment (T-MoCA) Cognition to measure cognition; cognitive impairment was defined as a score less than 18 on a scale of 0 to 22.

Results

• Researchers included 191 patients with 110 (57.6%) women; the mean (SD) age was 56.8 (16.7) years.
• For the primary outcome of interest, unadjusted analysis revealed a small increase in T-MoCA scores at 90 days compared with baseline among patients with and without delirium (with delirium, 0.69; 95% CI, −0.34 to 1.73 vs without delirium, 0.67; 95% CI, 0.17-1.16).
• Age, preoperative American Society of Anesthesiologists Physical Status Classification System score, preoperative cognitive impairment, and duration of anesthesia were included in the initial multivariate linear regression model.
• The only notable confounder was preoperative cognitive impairment: when adjusted for preoperative cognitive impairment, patients with delirium had a 0.70-point greater decrease in 90-day T-MoCA scores than those without delirium compared with their respective baseline scores (with delirium, 0.16; 95% CI, −0.63 to 0.94 vs without delirium, 0.86; 95% CI, 0.40-1.33).