Open AccessA Predictive Model for Intrathecal Opioid Dose Escalation for Chronic Non-Cancer Pain
Author(s) -
Rui Duarte,
Jacob Raphael,
Mohammad Sabbir Reza Haque,
Jane L. Southall,
Robert Ashford
Publication year - 2012
Publication title -
pain physician
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.31
H-Index - 99
eISSN - 2150-1149
pISSN - 1533-3159
DOI - 10.36076/ppj.2012/15/363
Subject(s) - medicine , opioid , morphine , intrathecal , cancer pain , chronic pain , medical record , anesthesia , retrospective cohort study , cancer , physical therapy , receptor
Background: Tolerance is defined as a phenomenon in which exposure to a drug results in adecrease of an effect or the requirement of a higher dose to maintain an effect. The fear of apatient developing opioid tolerance contributes regularly to the stigmatization and withholdingof intrathecal opioid therapy for chronic pain of non-cancer origin.Objectives: The aim of this study was to describe the intrathecal opioid dose escalationthroughout the years in chronic non-cancer pain patients. A secondary objective was thedevelopment of an intrathecal opioid dose predictive model.Study Design: Retrospective assessment of medical records.Setting: Department of Pain Management, Russells Hall Hospital, Dudley, United Kingdom.Methods: Medical records were reviewed and pump refill notes screened from the date ofimplant through November 2010 for 31 patients undertaking continuous intrathecal opioidtherapy. All the patients included had undertaken a minimum of 6 years of intrathecal therapywhen the data were collected.Results: Significant increases in the intrathecal morphine dose were verified between follow-upat one year and all subsequent observations, F (2.075, 62.238) = 13.858, 0 < 0.001, but ceasedto be significant from year 3 onwards, indicating stability of the morphine dose, F (3, 90) = 2.516,P = 0.63. A model that accounts for 76% of the variability of morphine doses at year 6 based onyear 2 assessment combined with duration of pain prior to initiation of intrathecal therapy wasdeveloped: year 6 dose = -0.509 + (1.296 x [year 2 dose]) + (0.061 x [duration of pain]).Limitations: Retrospective study.Conclusion: The opioid dose escalation observed throughout the years was modest and notsignificant following year 3 of therapy. The model developed has the potential to assist thephysician in the identification of a need for alternative treatment strategies. Furthermore, sincemany of the pump replacements are performed prior to year 6, it can also assist in the informeddecision of the benefits and risks of the maintenance of this therapy.Key words: Chronic pain, non-cancer pain, intrathecal opioid therapy, opioid dose escalation,predictive mode