Postoperative delirium associated with cognitive changes
A study done in the US showed that patients with delirium 24 to 72 hours after surgery are likely to experience changes in cognition.
The findings were reported in a prospective, single-centre, cohort study conducted from September 2017 to January 2018 with a total of 191 postsurgical patients (57.6 percent females; mean age, 56.8 years) who underwent major nonemergent or emergent surgical procedures. [JAMA Surg 2019, doi: 10.1001/jamasurg.2018.5093]
Results showed that when adjusted for preoperative cognitive impairment, patients with postoperative delirium had a 0.70-point greater decrease in 90-day telephone version of the Montreal Cognitive Assessment (T-MoCA) scores vs those without postoperative delirium, when compared with their respective baseline scores (with delirium, 0.16 [95 percent confidence interval (CI), -0.63 to 0.94] vs without delirium, 0.86 [95 percent CI, 0.40 to 1.33]).
Patients in the cohort with preoperative cognitive impairment who were not delirious had an increase in their T-MoCA score from baseline of 2.77 points, whereas those who were delirious had an increase of 2.07 points (difference, 0.7 points; 95 percent CI, -1.64 to 0.23).
“This cohort revealed multiple observations. Those with preoperative cognitive impairment appeared to have an improvement in cognition at 30 and 90 days after surgery. This increase was, however, attenuated if the patient experienced postoperative delirium,” explained the authors of the study.
For patients who experienced delirium on 1 out of 3 days after surgery, the decrease in T-MoCA score was 0.15 points (95 percent CI, -1.34 to 1.05; p=0.81). The decrease in T-MoCA score became greater for patients who experienced delirium on 2 out of 3 days (0.23 points; 95 percent CI, -1.72 to 1.26; p=0.76) and all 3 days postsurgery (0.96 points; 95 percent CI, -3.08 to 1.17; p=0.37).
“Our study also showed no difference in our outcome of interest when stratified by age, indicating that postoperative change in cognition is an age-independent process and that future prevention or treatment strategies for postoperative delirium should be directed to all adult surgical patients,” they added.
Patients included in the study underwent different types of surgery, with abdominal (22 percent) and urologic operations (18.3 percent) being the most common.
The mean length of postoperative hospital stay was 4.4 days, with patients either sent home without services (75.2 percent), or with physical therapy or home health care (19.9 percent). A small proportion of patients were sent to a skilled nursing facility (3.8 percent) or long-term acute or hospice care (1.1 percent) after discharge.
Limitations of the study include loss to follow-up despite efforts to assess all the participants. It is likely that some of the patients lost to follow-up had decreased cognition that might have precluded them from being assessed via telephone calls.
Patients with postoperative delirium were reported to have increased mortality after 3 months and 1 year, increased duration of hospitalization, and increased odds of being transferred to a skilled nursing facility after discharge. [PLoS One 2015;10:e0136071; JAMA 2010;304:443-451]