Preoperative 6-Minute Walk Distance Is Associated With Postoperative Cognitive Dysfunction

Background: Postoperative cognitive dysfunction (POCD) is a neurologic dysfunction that occurs after surgery. POCD persists for a long period, ranging from weeks to months, and affects a patient's quality of life. A 6-minute walk distance (6MWD) has been used to predict postoperative complications after several operations. The present study investigated whether there was an independent association of a low preoperative 6MWD with POCD in patients who underwent cardiac operations. Methods: The study included 181 patients who underwent a cardiac operation. The 6MWD was performed prospectively on admission for the operation. POCD was defined as a decrease of 2 points or more in a patient's Mini-Mental State Examination score. POCD developed in 51 (28%) of these patients. Patients were categorized into a POCD or a non-POCD group, and the perioperative variables were compared between the groups. Multivariable logistic regression analysis was performed to identify risk factors for the development of POCD. Results: The patients were a mean age of 71.4 years. The POCD group showed a significantly lower 6MWD (median, 400 m) than the non-POCD group (median, 450 m). The 6MWD, intensive care unit length of stay, age, and Mini-Mental State Examination score were identified as independent risk factors for POCD by multivariable analysis. The odds ratio for each increase of 50 m in the 6MWD was 0.807 for POCD. Conclusions: The 6MWD is useful in identifying patients with a higher chance of developing POCD after a cardiac operation.