The Prevalence and Impact of Undiagnosed Mild Cognitive Impairment in Elderly Patients Undergoing Thoracic Surgery: A Prospective Cohort Study

Abstract

The objective of this study was to explore the prevalence of undiagnosed mild cognitive impairment (MCI) and its association with adverse outcomes in elderly patients undergoing thoracic surgery. A prospective cohort study. Large tertiary medical center. The authors enrolled 170 patients aged 65 years or older who were scheduled for thoracic surgery between November 7, 2018, and April 1, 2019, at the Shanghai Chest Hospital. Patients with a history of schizophrenia or dementia disease, uncorrected vision or hearing impairment, and refusal to participate were excluded. A total of 154 elderly patients completed the Chinese version of the Montreal Cognitive Assessment (MoCA) test preoperatively and were included in the final analysis. They were categorized into a normal group (MoCA ≥ 26 scores, group N) and an abnormal group (MoCA < 26 scores, group AN) based on test results. Delirium was assessed with the Confusion Assessment Method twice daily during the first 3 postoperative days. The primary outcome was the incidence of postoperative delirium (POD). Secondary outcomes included the incidence of postoperative pulmonary complications (PPCs), cardiovascular complications, other complications, intensive care unit (ICU) stay, and the hospital length of stay (LOS). The incidence of MCI before thoracic surgery in elderly patients was 49.4% (76 of 154). Compared with group N, MCI could increase the incidence of POD (14.1% v 30.3%, p = 0.016) and median LOS (4 d v 5 d, p = 0.016). However, the differences in pulmonary complications, cardiovascular and other complications, and ICU stay were not significant. Multivariable logistic regression analysis showed preoperative MCI (OR = 2.573, 95% CI =1.092 to 6.060, p = 0.031) as an independent risk factor of POD. Compared with the elderly patients without POD, POD could increase the risk of PPCs (17.5% v 35.3%, p = 0.026) and median LOS (4 d v 5 d, p < 0.001). The incidence of MCI before thoracic surgery in elderly patients was higher and associated with a higher rate of adverse postoperative outcomes. The findings may be important for preoperative patient counseling, operative planning, and eventually reducing potential risk exposure and related outcomes.