The journal of pain : official journal of the American Pain Society
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Habituation (ie, decreases in responding) and sensitization (ie, increases in responding) after prolonged or repeated exposures to a fixed stimulus have been identified as important in adaptation to repeated or prolonged noxious stimulation. Determinants of habituation or sensitization are poorly understood, and experimental investigation of habituation of pain ratings have generally relied on pain reports and statistical techniques that average responses across a group of participants. Using a cross-sectional design, the current study used multilevel growth curve analyses to examine changes in the nociceptive flexion reflex (NFR), a spinal nociceptive withdrawal reflex, and pain ratings in response to 12 repeated, constant intensity, noxious electrocutaneous stimuli. ⋯ However, a substantial subgroup of participants exhibited the opposite pattern of change. In conditional models, behavioral inhibition, b = .10, P = .003, and behavioral activation, b = -.07, P = .07, independently interacted with the growth curve to predict changes in NFR, but not pain ratings, across the 12 stimuli. These findings provide preliminary experimental support for Jensen and colleagues' 2-factor model of pain experience and implicate a role for approach and avoidance motivations in descending modulation of NFR.
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Pain acceptance is a robust predictor of adjustment to chronic pain; however, the dynamics of pain acceptance in daily life are largely unexamined. Furthermore, research on pain acceptance in those with pain and physical disability is needed. To examine pain acceptance in daily life, we collected 7 days of ecological momentary assessments of pain intensity and pain interference (5 times per day) with continuous accelerometry (physical activity) in 128 individuals with chronic pain and spinal cord injury. ⋯ The activities engagement component of pain acceptance was a slightly more robust driver of these interaction effects; whereas activities engagement significantly moderated the association between momentary pain and pain interference as well as physical activity, pain willingness exerted a significant moderating effect on the momentary association between pain intensity and pain interference only. These findings suggest that both components contribute to the decoupling effects of pain acceptance. Task persistence did not show the same moderating effects, indicating that pain acceptance may be unique from other types of behavioral pain coping in its ability to decouple expected associations between pain intensity, pain interference, and physical activity.
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Increased pressure pain sensitivity and impaired descending pain control have been associated with chronic pain, but knowledge on the variability in the adult general population is lacking. Pressure pain thresholds (PPTs) and descending pain control assessed using conditioned pain modulation (CPM) were recorded in a randomly selected sample (n = 2,199, 53% female) of the Danish adult general population aged 18 to 70 years. PPTs were recorded over the tibialis anterior muscle and the upper trapezius muscle. ⋯ For the trapezius muscle, high perceived stress was associated with lower PPTs (P < .02), whereas an interaction was found between body mass index and sex. CPM potency was lower in female compared with male participants (P ≤ .003), whereas no association with age was found. Higher level of education (P ≤ .05), premature withdrawal from the cold pressor test (P ≤ .02), and high visual analog scale score (P ≤ .02) were associated with a larger CPM response.
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Chronic cancer pain is a serious complication of malignancy or its treatment. Currently, no comprehensive, universally accepted cancer pain classification system exists. Clarity in classification of common cancer pain syndromes would improve clinical assessment and management. Moreover, an evidence-based taxonomy would enhance cancer pain research efforts by providing consistent diagnostic criteria, ensuring comparability across clinical trials. As part of a collaborative effort between the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION) and the American Pain Society (APS), the ACTTION-APS Pain Taxonomy initiative worked to develop the characteristics of an optimal diagnostic system. After the establishment of these characteristics, a working group consisting of clinicians and clinical and basic scientists with expertise in cancer and cancer-related pain was convened to generate core diagnostic criteria for an illustrative sample of 3 chronic pain syndromes associated with cancer (ie, bone pain and pancreatic cancer pain as models of pain related to a tumor) or its treatment (ie, chemotherapy-induced peripheral neuropathy). A systematic review and synthesis was conducted to provide evidence for the dimensions that comprise this cancer pain taxonomy. Future efforts will subject these diagnostic categories and criteria to systematic empirical evaluation of their feasibility, reliability, and validity and extension to other cancer-related pain syndromes. ⋯ The ACTTION-APS chronic cancer pain taxonomy provides an evidence-based classification for 3 prevalent syndromes, namely malignant bone pain, pancreatic cancer pain, and chemotherapy-induced peripheral neuropathy. This taxonomy provides consistent diagnostic criteria, common features, comorbidities, consequences, and putative mechanisms for these potentially serious cancer pain conditions that can be extended and applied with other cancer-related pain syndromes.
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Randomized Controlled Trial
Prescription Opioid Taper Support for Outpatients with Chronic Pain: A Randomized Controlled Trial.
Patients receiving long-term opioid therapy for chronic pain and interested in tapering their opioid dose were randomly assigned to a 22-week taper support intervention (psychiatric consultation, opioid dose tapering, and 18 weekly meetings with a physician assistant to explore motivation for tapering and learn pain self-management skills) or usual care (N = 35). Assessments were conducted at baseline and 22 and 34 weeks after randomization. Using an intention to treat approach, we constructed linear regression models to compare groups at each follow-up. ⋯ Pain severity ratings (0-10 numeric rating scale) decreased in both groups at 22 weeks, with no significant difference between groups (adjusted mean difference = -.68; 95% confidence interval, -2.01 to .64; P = .30). The taper support group improved significantly more than the usual care group in self-reported pain interference, pain self-efficacy, and prescription opioid problems at 22 weeks (all P-values < .05). This taper support intervention is feasible and shows promise in reducing opioid dose while not increasing pain severity or interference.