title: Review of the performance of quantitative sensory testing methods to detect hyperalgesia in chronic pain patients on long-term opioids.
abstract: BACKGROUND
  Opioid-induced hyperalgesia is a clinical syndrome whereby patients on long-term opioids become more sensitive to pain while taking opioids. Opioid-induced hyperalgesia is characterized by increased pain intensity over time, spreading of pain to other locations, and increased pain sensation to external stimuli. To characterize opioid-induced hyperalgesia, laboratory methods to measure hyperalgesia have been developed. To determine the performance of these methods, the authors conducted a systematic review of clinical studies that incorporate measures of hyperalgesia in chronic pain patients on long-term opioids.
  
  
  METHODS
  PubMed and Cochrane databases were searched (terms: opioid induced hyperalgesia, study or trial, and long-term or chronic). Studies published in English were selected if they were conducted in chronic pain patients on long-term opioids and incorporated measures of hyperalgesia; acute/single-dose studies and/or conducted in healthy volunteers were excluded.
  
  
  RESULTS
  Fourteen articles made the final selection (11 were selected from the search and 3 others were found from additional sources); there was one randomized controlled trial, one prospective controlled study, three prospective uncontrolled studies, and nine cross-sectional observation studies. Hyperalgesia measurement paradigms used included cold pain, heat pain, pressure pain, electrical pain, ischemic pain, and injection pain. Although none of the stimuli were capable of detecting patients' hyperalgesia, heat pain sensitivity showed some promising results.
  
  
  CONCLUSIONS
  None of the measures reviewed herein met the criteria of a definitive standard for the measurement of hyperalgesia. Additional studies that use improved study design should be conducted.
authors.affiliation: From the Analgesic Solutions, Natick, Massachusetts (N.P.K., F.C.P.); and Brigham and Women's Hospital, Department of Anesthesiology, Perioperative, and Pain Medicine, Harvard Medical School, Chestnut Hill, Massachusetts (R.R.E.).
authors.forename: Nathaniel P
authors.initials: NP
authors.lastname: Katz
authors.forename: Florence C
authors.initials: FC
authors.lastname: Paillard
authors.forename: Robert R
authors.initials: RR
authors.lastname: Edwards
mesh_terms: D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000009:adverse effects*; D059350:Chronic Pain / Q000175:diagnosis / Q000188:drug therapy* / Q000453:epidemiology; D002986:Clinical Trials as Topic / Q000592:standards; D004334:Drug Administration Schedule; D006801:Humans; D006930:Hyperalgesia / Q000139:chemically induced* / Q000175:diagnosis* / Q000453:epidemiology
chemical_list: D000701:Analgesics, Opioid