Psychological Effects of Explicit Recall under Sedation and after Surgery (PEERS): a Prospective Cohort Study on 2500 Patients

Background: Explicit recall occurring during sedation/regional anaesthesia is common but has long been assumed to have no sequelae. We conducted a prospective cohort study to determine the incidence of explicit recall experience under sedation/regional anaesthesia, as well as, to assess the recall experiences that are associated with psychological consequences. Methods: We prospectively recruited 2,500 adults who underwent elective total hip or knee arthroplasty under sedation/regional anaesthesia from September 2021 to March 2024 at University Hospital in London, ON, Canada. The primary exposure was recall experience, assessed using the modified Brice questionnaire. The co-primary outcomes included probable depression (defined as a Patient Health Questionnaire-score ≥ 8) and suspected post-traumatic stress disorder symptoms (defined as a Posttraumatic Stress Disorder Checklist – Civilians ≥ 13) at 6 weeks postoperatively. The association between specific recall experiences and the co-primary outcomes was evaluated by multivariable regression analysis. Additionally, we assessed the incidence and mental health burden related to the psychological effects of surgery in the entire cohort. Results: A total of 2,138 patients were included in the final analysis. Explicit recall was reported by 475 participants (22.2%) but was not associated with the co-primary outcomes. Regarding surgery's overall impact, 61 participants (5%) developed new probable depression, 105 participants (5%) reported suspected post-traumatic stress disorder, and 95 patients (4.4%) developed new suicidal ideation postoperatively. We estimate that 1 in 18 patients required new psychiatric consultation. Conclusion: Explicit recall per se during sedation/regional anaesthesia did not increase the odds of developing psychiatric illness. Surgery itself carries significant risks of triggering depression and post-traumatic stress disorder that are severe enough to reach levels associated with suicidal ideation, requiring immediate mental care. This study reveals a significant, yet underappreciated, mental healthcare burden. Clinicaltrial.gov #: NCT04747379