title: Co-morbid pain and opioid addiction: long term effect of opioid maintenance on acute pain.
abstract: BACKGROUND
  Medication assisted treatment for opioid dependence alters the pain experience. This study will evaluate changes pain sensitivity and tolerance with opioid treatments; and duration of this effect after treatment cessation.
  
  
  METHODS
  120 Individuals with chronic pain were recruited in 4 groups (N = 30): 1-methadone for opioid addiction; 2-buprenorphine for opioid addiction; 3-history of opioid maintenance treatment for opioid addiction but with prolonged abstinence (M = 121 weeks; SD = 23.3); and 4-opioid naïve controls. Participants completed a psychological assessment and a cold water task including, time to first pain (sensitivity) and time to stopping the pain task (tolerance). Data analysis used survival analyses.
  
  
  RESULTS
  A Kaplan-Meier-Cox survival analysis showed group differences for both pain sensitivity (log rank = 15.50; p < .001) and tolerance (log rank = 20.11; p < .001). Current or historical use of opioid maintenance resulted in differing pain sensitivity compared to opioid naïve (p's < .01). However, tolerance to pain was better among those with a history of opioid maintenance compared to active methadone patients (p < .05), with the highest tolerance found among opioid naïve control group participants (p's < .001). Correlations within the prolonged abstinent group indicated pain tolerance was significantly improved as length of opioid abstinence increased (R = .37; p < .05); but duration of abstinence did not alter sensitivity (ns).
  
  
  CONCLUSIONS
  Among individuals with a history of prolonged opioid maintenance, there appears to be long-term differences in pain sensitivity that do not resolve with discontinuation of opioid maintenance. Although pain sensitivity does not change, pain tolerance does improve after opioid maintenance cessation. Implications for treating co-morbid opioid addiction and pain (acute and chronic) are discussed.
authors.affiliation: Division of Addiction Psychiatry, Dept of Psychiatry, University of Massachusetts Medical School, Worcester, MA 01655, United States. Electronic address: Amy.wachholtz@umassmemorial.org.
authors.forename: Amy
authors.initials: A
authors.lastname: Wachholtz
authors.affiliation: Division of Addiction Psychiatry, Dept of Psychiatry, University of Massachusetts Medical School, Worcester, MA 01655, United States.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Gonzalez
mesh_terms: D059787:Acute Pain / Q000188:drug therapy* / Q000453:epidemiology* / Q000523:psychology; D000328:Adult; D000701:Analgesics, Opioid / Q000627:therapeutic use*; D016739:Behavior, Addictive / Q000188:drug therapy / Q000453:epidemiology / Q000523:psychology; D002047:Buprenorphine / Q000627:therapeutic use; D015897:Comorbidity; D005260:Female; D006801:Humans; D008297:Male; D008691:Methadone / Q000627:therapeutic use; D008875:Middle Aged; D058850:Opiate Substitution Treatment / Q000523:psychology / Q000639:trends*; D009293:Opioid-Related Disorders / Q000188:drug therapy* / Q000453:epidemiology* / Q000523:psychology; D010147:Pain Measurement / Q000379:methods / Q000523:psychology; D017288:Pain Threshold / Q000187:drug effects / Q000523:psychology; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000701:Analgesics, Opioid; D002047:Buprenorphine; D008691:Methadone
keywords: Abstinence; Buprenorphine; Comorbidity; Methadone; Opioid addiction; Pain