The purpose of this study is to determine the effect of opioid taper on pain sensitivity in patients with chronic pain. In a well-characterized sample of men and women with chronic neuropathic pain on high-dose opioid therapy, experimental pain responses (cold-pressor, quantitative sensory testing) will be serially described over the course of and following an individualized opioid taper. In addition, functional improvements and subject-level predictors of response will be described.
The overall Specific Aim of this proposal is to determine the effect of opioid taper on pain sensitivity in patients with chronic pain. Specifically, in a well-characterized sample of men and women with chronic neuropathic pain and receiving high-dose opioid therapy (\>100mg morphine equivalents/day \[MED\]), experimental pain responses will be serially described over the course of an individualized opioid taper to a safer dose of 90mg MED for up to 12 months. Changes will be inspected within-subject over time, and pain perception will be measured with two valid and reliable experimental pain induction techniques commonly used to measure OIH (cold-pressor, quantitative sensory testing); in addition, related functional improvements and subject-level predictors of response will be described. Hypothesis 1. Subjects undergoing opioid taper will have improved pain responses over time compared to within-subject baseline as measured by cold-pressor and quantitative sensory pain testing. Hypothesis 2. Improvements in experimental pain responses will be positively related to improved functional outcomes compared to within-subject baseline as measured by the PROMIS physical, mental and social health measures. Hypothesis 3. Degree of improvement in experimental pain responses related to opioid taper will be predicted by demographic, pain, and opioid use history characteristics of the subject. Data showing that pain perception improves as opioids are withdrawn would provide an evidence-based, mechanistic rationale for opioid taper in patients with chronic pain and have the potential to support a sea-change in opioid prescription practices. In that ongoing opioid therapy brings with it significant health risks for the patient and the community, it is critical that empirical evidence of its efficacy be demonstrated to balance the benefits with the risks of adverse events, potential misuse and abuse, and patient safety.
Study Type
OBSERVATIONAL
Enrollment
7
Pain Responses: The primary dependent variable, pain, will be measured using two highly reliable and valid pain induction techniques, the CPT and QST, employing procedures consistent with those described in the literature. Order of pain testing will vary, and three aspects of the pain response will be captured at each study session: evoked pain; temporal summation; and conditioned pain modulation, which map on to the hypothesized peripheral, spinal and supra-spinal mechanisms of OIH. Protocols for each assay have been uploaded.
Penn Pain Medicine Center Tuttleman Center
Philadelphia, Pennsylvania, United States
Pain Perception Measured Using the Cold-pressor Test (CPT)
Pain perception will be measured using the cold-pressor test (CPT) employing procedures consistent with those described in the literature. Order of pain testing will vary, and three aspects of the pain response will be captured at each study session: evoked pain; temporal summation; and conditioned pain modulation, which map on to the hypothesized peripheral, spinal and supra-spinal mechanisms of OIH. Reported are cold-pressor pain tolerance prior to and following taper.
Time frame: up to one year (length of taper individualized and varies)
Conditioned Pain Modulation Measured Using the Quantitative Sensory Testing (QST)
Conditioned pain modulation will be measured using the quantitative sensory testing (QST) employing procedures consistent with those described in the literature to capture supra-spinal mechanisms of OIH. To detect conditioned modulation, the subject is asked to verbally report the severity of pain experienced on a visual analogue scale (0- no pain, 10-worst pain ever) to a three-second painful heat stimulus (47○C) delivered at 12-15 second intervals, in the presence or absence of the non-dominant limb being immerged in a cold-water bath (12○C). The reported value is the difference between the average of pain scores reported in the absence of vs. the presence of the counter-stimulation. Reported are changes in the conditioned pain modulation assay both prior to and following taper. Taper is individualized thus length of taper varies between subjects.
Time frame: up to one year (individualized, variable taper length)
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