The association between preoperative chronic pain and postoperative delirium in elderly patients undergoing elective orthopedic surgery

Background Postoperative delirium (POD) is an acute and common postoperative complication that can increase morbidity and mortality. The evidence regarding the association between preoperative chronic pain and POD is inconsistent. This study aims to explore the relationship between preoperative chronic pain and POD. Methods This prospective cohort study consecutively enrolled 200 elderly patients undergoing elective orthopedic surgery. POD occurring within 7 days was assessed using the 3-min Diagnostic Interview for Confusion Assessment Method (3D-CAM). Chronic pain was defined as pain lasting ≥ 3 months, with intensity assessed by VAS preoperatively. Demographic and perioperative baselines were compared between delirium and non-delirium groups. Univariate and multivariate logistic regression were used to identify POD risk factors. Subgroup analyses focus on chronic pain patients were performed to explore the risk factors of developing POD among them. Results Among the 200 enrolled patients (median age, 69 years; ASA II/III, 106/94), POD occurred in 33% (66/200) and preoperative chronic pain occurred in 58.5% (117/200). Univariate and multivariable logistic regression analyses showed significant association between preoperative chronic pain and POD among elder population (unadjusted OR = 2.039, 95% CI: 1.090–3.811; adjusted OR = 2.488, 95% CI: 1.282–4.837, P = 0.007). A subgroup analysis of chronic pain patients revealed that current pain intensity (VAS scores) was associated with the increased risk of POD (OR = 1.858, 95% CI: 1.291–2.675, P < 0.001). Conclusion Preoperative chronic pain is associated with the increased risk of POD in the elderly patients undergoing elective orthopedic surgery. Furthermore, a significant association between current pain intensity assessed by VAS and POD was found among older adults with chronic pain.