Incidence of Cognitive Decline 5 Years after Orthopaedic Surgery According to Method of Assessment

Abstract Background Older adults who undergo elective surgery may be at risk of an altered cognitive trajectory leading to long‐term decline. We investigated the incidence of cognitive decline in the elderly following elective non‐cardiac surgery five years post‐operatively and examined whether differences in classification criteria for cognitive outcomes resulted in different incidence rates. Method We prospectively studied older adults following orthopaedic surgery, alongside non‐surgical control participants. All participants completed a battery of neuropsychological tests before surgery and again five years postoperatively. We classified Postoperative Cognitive Dysfunction (POCD), (a change‐based construct historically used in anesthesiology and surgery) as a decline of two standard deviations (SD) on two or more cognitive tests compared to controls. We also assessed Neurocognitive Disorders (NCD) relative to change in controls, a term recently introduced to align cognitive disorders with community medicine. Major NCD was defined by a decline of two SD on any test, accompanied by a subjective memory complaint and observed decline in instrumental activities of daily living. Mild NCD was classified as a memory complaint and a decline of one SD on at least one test. Result From an initial 300 participants enrolled, 227 participants (surgical = 199, non‐surgical control = 34) completed the five year follow‐up. Average (SD) follow‐up age was 74.8 (6. 6) years and 154 (67.8%) were female. We identified POCD at five years in 28 (14.2%), and major NCD in 38 (19.3%) participants. Mild NCD was more common, occurring in 81 (41.1%) participants. Cognitive decline five years postoperatively was associated with increasing age, whereas education history and anesthetic technique (spinal or GA) were not significantly associated. Further analyses will determine the role of cardiovascular risk factors. Conclusion We found both overlap and differences in the incidence rate of cognitive decline according to the criteria used for classification. Regardless of classification criteria and nomenclature, we found higher rates of cognitive decline amongst non‐cardiac surgical patients compared to rates reported in the general population. Our findings provide support that even elective, non‐cardiac surgical procedures under anesthesia are associated with a faster rate of cognitive decline amongst older adults. Possible pathophysiological mechanisms, including cardiovascular factors, will be discussed.