title: The impact of postoperative pain on the development of postoperative delirium.
abstract: We performed a prospective observational study to examine the role of postoperative pain and its treatment on the development of postoperative delirium. Pain was measured in direct patient interviews using a visual analog scale (VAS) and was assessed for pain at rest, pain with movement, and maximal pain over the previous 24 h. Postoperative delirium was diagnosed during these interviews by using the confusion assessment method (CAM) and/or by using data from the medical record and the hospital's nursing intensity index. The method of postoperative analgesia, type of opioid, and cumulative opioid dose were also recorded. After controlling for known preoperative risk factors for delirium (age, alcohol abuse, cognitive function, physical function, serum chemistries, and type of surgery), higher pain scores at rest was associated with an increased risk of delirium over the first 3 postoperative days (adjusted risk ratio 1.20, P = 0.04). Pain with movement and maximal pain were not associated with delirium. Method of postoperative analgesia, type of opioid, and cumulative opioid dose were not associated with an increased risk of delirium. We conclude that more effective control of postoperative pain reduces the incidence of postoperative delirium.
  
  
  CONCLUSIONS
  We performed daily interviews in a large population of patients undergoing noncardiac surgery to measure their level of pain and development of delirium. We found an association between higher pain levels at rest and the development of delirium. Our results suggest that better control of postoperative pain may reduce this serious complication.
authors.affiliation: Department of Anesthesia, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: E P
authors.initials: EP
authors.lastname: Lynch
authors.forename: M A
authors.initials: MA
authors.lastname: Lazor
authors.forename: J E
authors.initials: JE
authors.lastname: Gellis
authors.forename: J
authors.initials: J
authors.lastname: Orav
authors.forename: L
authors.initials: L
authors.lastname: Goldman
authors.forename: E R
authors.initials: ER
authors.lastname: Marcantonio
mesh_terms: D000203:Activities of Daily Living; D000367:Age Factors; D000368:Aged; D000437:Alcoholism / Q000150:complications; D000698:Analgesia; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000627:therapeutic use; D001774:Blood Chemical Analysis; D003071:Cognition; D003221:Confusion / Q000175:diagnosis / Q000209:etiology / Q000451:nursing; D003693:Delirium / Q000175:diagnosis / Q000209:etiology* / Q000451:nursing / Q000517:prevention & control; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D009068:Movement; D009730:Nursing Assessment; D016017:Odds Ratio; D010147:Pain Measurement; D010149:Postoperative Pain / Q000150:complications* / Q000188:drug therapy / Q000451:nursing; D011183:Postoperative Complications / Q000175:diagnosis / Q000451:nursing / Q000517:prevention & control; D011446:Prospective Studies; D012146:Rest; D012307:Risk Factors; D013514:Surgical Procedures, Operative
chemical_list: D000701:Analgesics, Opioid