title: Hyperalgesia induced by low-dose opioid treatment before orthopaedic surgery: An observational case-control study.
abstract: BACKGROUND
  Chronic pain and opioid consumption may trigger diffuse hyperalgesia, but their relative contributions to pain vulnerability remain unclear.
  
  
  OBJECTIVE
  To assess preoperative opioid-induced hyperalgesia and its postoperative clinical consequences in patients with chronic pain scheduled for orthopaedic surgery.
  
  
  METHODS
  A prospective observational study.
  
  
  METHODS
  Raymond Poincare teaching hospital.
  
  
  METHODS
  Adults with or without long-term opioid treatment, scheduled for orthopaedic surgery.
  
  
  METHODS
  Preoperative hyperalgesia was assessed with eight quantitative sensory tests, in a pain-free zone.
  
  
  METHODS
  Postoperative morphine consumption and pain intensity were evaluated using a numerical rating scale (NRS) in the recovery room and during the first 72 h.
  
  
  RESULTS
  We analysed results from 68 patients (28 opioid-treated patients and 40 controls). Mean daily opioid consumption was 42 ± 25 mg of morphine equivalent. The opioid-treated group displayed significantly higher levels of preoperative hyperalgesia in three tests: heat tolerance threshold (47.1°C vs. 48.4°C; P = 0.045), duration of tolerance to a 47°C stimulus (40.2 vs. 51.1 s; P = 0.03) and mechanical temporal summation [1.79 vs. 1.02 (ΔNRS10-1); P = 0.036]. Patients in the opioid-treated group consumed more morphine (19.1 vs. 9.38 mg; P = 0.001), had a higher pain intensity (7.6 vs. 5.5; P = 0.001) in the recovery room and a higher cumulative morphine dose at 72 h (39.8 vs. 25.6 mg; P = 0.02).
  
  
  CONCLUSIONS
  Chronic pain patients treated with low doses of opioid had hyperalgesia before surgery. These results highlight the need to personalise the management of patients treated with opioids before surgery.
  
  
  BACKGROUND
  ID-RCB 2011-A00304-37.
authors.affiliation: From the Service d'Anesthésie Réanimation Chirurgicale, Hôpital Raymond Poincaré, Assistance Publique Hôpitaux de Paris, Garches (NH, DF,VM), INSERM, U-987, Hôpital Ambroise Paré, Centre d'Evaluation et de Traitement de la Douleur, Boulogne Billancourt (DF,FP-J,VM), and Université Versailles Saint-Quentin, Versailles, France (DF).
authors.forename: Nabil
authors.initials: N
authors.lastname: Hina
authors.forename: Dominique
authors.initials: D
authors.lastname: Fletcher
authors.forename: Frédérique
authors.initials: F
authors.lastname: Poindessous-Jazat
authors.forename: Valéria
authors.initials: V
authors.lastname: Martinez
mesh_terms: D000368:Aged; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000009:adverse effects*; D016022:Case-Control Studies; D059350:Chronic Pain / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D005260:Female; D005602:France; D006784:Hospitals, Teaching; D006801:Humans; D006930:Hyperalgesia / Q000139:chemically induced* / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage / Q000009:adverse effects*; D019637:Orthopedic Procedures / Q000009:adverse effects*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects; D010149:Postoperative Pain / Q000139:chemically induced* / Q000175:diagnosis; D011446:Prospective Studies; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000701:Analgesics, Opioid; D009020:Morphine