The risk factors for postoperative delirium in adult patients after hip fracture surgery: a systematic review and meta-analysis

Objectives: Postoperative delirium (POD) is the most common complication in patients after hip fracture surgery, and the incidence of POD is associated with mortality and disability in patients following hip fracture surgery. Therefore, this study aimed to identify the individual as well as anesthetic and operative risk factors associated with the POD in adult patients after hip fracture surgery.

Methods: We searched relevant articles published to February 2020 in Cochrane Library, PubMed, and Embase. Studies involving adult patients who underwent hip fracture surgery were regarded as relevant if the studies contained the individual or anesthetic and surgical characteristics of participants. The pooled relative risk ratios (RRs) or weight mean difference of the variables were estimated by the Mantel-Haenszel or Inverse-Variance methods.

Results: A total of 44 studies were included, which altogether included 104572 participants with hip fracture surgery (17703 patients with POD and 86869 patients without POD) and the incidence of POD was 16.93%. A total of 14 risk factors, classified into two categories which were individual as well as anesthetic and operative factors, were identified originally, which included age (weight mean difference [WMD]:2.33;95% confidential interval [CI]: 1.64-3.03), sex (RR: 0.89; 95% CI:0.85-0.93), American society of Anesthesiologists classification(RR:0.56; 95%CI:0.51-0.59), body mass index (WMD:-0.62; 95%CI:-0.81 to -0.44), function dependency(RR:1.52; 95% CI:1.24-1.87), visual impairment (RR:1.62; 95% CI: 1.16-2.27), smoking (RR:0.86; 95% CI:0.79-0.94), preoperative delirium (RR: 2.71; 95% CI: 2.50-2.72), dementia (RR:2.60; 95% CI:2.50-2.72), hypertension (RR: 1.10; 95% CI:1.04-1.15), chronic obstructive pulmonary disease (RR:1.08; 95% CI: 1.01-1.16), regional anesthesia (RR:1.20; 95% CI: 1.01-1.43), transfusion (RR: 1.41; 95% CI: 1.22-1.63), and elective surgery (RR: 0.91; 95% CI: 0.84-0.99).

Conclusions: Patients possessed above risk factors might be high-risk patients. Clinician should maintain keen vigilance at those patients.