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The opioid epidemic is a significant public health concern linked to chronic pain. Despite efforts to change opioid prescribing practices for chronic pain, opioid-involved overdoses remain at an all-time high. Research focused on identifying individual difference factors for problematic opioid misuse in the context of chronic pain have identified certain psychological variables that may confer heightened risk for opioid-related problems. Anxiety sensitivity, or fear of anxiety-related physical sensations, has been linked to opioid-related problems among adults with chronic pain. Yet, it is possible that these relations may not be distributed equally in society, and sex differences may be one avenue by which these relations differ. Therefore, the current study examined the moderating role of sex on the relation between anxiety sensitivity, current opioid misuse, and severity of opioid dependence among 428 adults (74.9% female, M = 38.28 years, SD = 11.06) with chronic pain. Results indicated that the relation between anxiety sensitivity and current opioid misuse (ΔR = 0.005, B = 0.12, SE = 0.06, p = 0.04), and opioid dependence (ΔR = 0.01, B = 0.04, SE = 0.02, p = 0.007) was stronger for males compared to females. These results suggest that anxiety sensitivity may be associated with opioid-related problems to a greater extent for males than females. Continued research is needed to examine how these sex differences may impact clinical treatment for opioid-related problems.
Learn More >Post-traumatic Stress Disorder (PTSD) commonly co-occurs with chronic pain. Although PTSD symptoms are associated with negative health outcomes in patients with chronic pain, PTSD is typically under-detected and under-treated in outpatient pain settings. There is a need for rapid, brief screening tools to identify those at greatest risk for severe PTSD symptoms. To achieve that goal, our aim was to use item response theory (IRT) to identify the most informative PTSD symptoms characterizing severe PTSD in patients with chronic pain.
Learn More >To study the various pain assessment tools based on their psychometric properties and ease of use.
Learn More >To describe morphological changes associated with degeneration and regeneration of large fibers in the skin using a model of chronic compression of the median nerve.
Learn More >There is no consensus regarding the effectiveness of Transcutaneous Electrical Nerve Stimulation (TENS) for chronic musculoskeletal or low back pain. A review of previous trial methodology identified problems with treatment fidelity. Qualitative research with experienced TENS users identified specific contexts for TENS use, leading to individualised outcomes. There is little information available to guide the selection of Patient Reported Outcome Measures (PROMs) appropriate for TENS evaluation.
Learn More >Drawing on advances in chronic pain metrics, a simplified Graded Chronic Pain Scale Revised (GCPS-R) was developed to differentiate mild, bothersome and high impact chronic pain. GCPS-R was validated among adult enrollees of two health plans (N=2021). In this population, the prevalence of chronic pain (pain present most or every day, prior 3 months) was 40.5%: 15.4% with mild chronic pain (lower pain intensity and interference); 10.1% bothersome chronic pain (moderate to severe pain intensity with lower life activities interference); and 15.0% high impact chronic pain (sustained pain-related activity limitations). Persons with mild chronic pain versus those without chronic pain showed small differences on ten health status indicators (unfavorable health perceptions, activity limitations, receiving long-term opioid therapy), with non-significant differences for 7 of 10 indicators. Persons with bothersome versus mild chronic pain differed significantly on 6 of 10 indicators (e.g., negative pain coping beliefs, psychological distress, unfavorable health perceptions and pain-related interference with overall activities). Persons with high impact chronic pain differed significantly from those with mild chronic pain on all 10 indicators. Persons with high impact chronic pain, relative to those with bothersome chronic pain, were more likely to have substantial activity limitations (significant differences for 4 of 5 disability indicators) and more often received long-term opioid therapy. GCPS-R strongly predicted five activity limitation indicators with area under receiver operating characteristic curve coefficients of 0.76 to 0.89. We conclude that the 5 item GCPS-R and its scoring rules provide a brief, simple and valid method for assessing chronic pain.
Learn More >The complex mechanisms underlying migraine are not entirely understood. It has been suggested that descending endogenous pain modulation is an important contributing factor, although research is controversial. A frequently used method to quantify the inhibitory pain modulation system is offset analgesia (OA), defined as a disproportionally large decrease in pain perception in response to a small decrease of painful stimulation. The aim of this study is to evaluate the OA response in patients with migraine and healthy controls, measured at the forehead (trigeminal, V1) and forearm (extra-trigeminal). Patients with episodic migraine during the headache free interval (n=26) and age and sex matched headache-free controls (n=26) were included in this cross-sectional study. All participants underwent an individualized OA paradigm consisting of three-stimulus offset trials and three constant temperature trials examined at both, a trigeminal and an extra-trigeminal test site. Items from the quantitative sensory testing protocol were additionally included. In contrast to the extra-trigeminal area, a reduced offset analgesia response was shown in the trigeminal area in patients with migraine compared to healthy controls (p<0.01, MD: 13.7, 95%CI: 3.8; 23.6). Statistically significant differences between the trigeminal area and the extra-trigeminal area were neither observed in healthy controls nor in patients with migraine (p>0.05). Mechanical detection, mechanical pain threshold, warm detection and heat pain threshold showed no significant differences between groups or test sites (p>0.05). In summary, patients with episodic migraine in the headache free interval exhibited somatotopically specific differences in endogenous pain modulation.
Learn More >Chronic pain is mainly treated with opioid analgesics such as morphine. However, the use of these substances can cause adverse effects, including dependence and tolerance, necessitating the discovery of a new approach to analgesic therapies. The transient receptor potential vanilloid 1 (TRPV1) is linked to thermal sensibility and has been considered as a new therapeutic option for pain treatment. This study aims to investigate the antinociceptive effect and toxicity of SB-366791, a TRPV1 antagonist. Morphine-tolerant and morphine non-tolerant Swiss mice were submitted to the hot plate and thermal tail flick tests. Toxicological evaluations of the genotoxic and mutagenic activities of SB-366791 were assessed using a comet assay and micronucleus test, and the Salmonella/microsome mutagenicity assay. In the hot plate test, intrathecal injection of SB-366791 or morphine resulted in significantly increased antinociception in non-tolerant mice. SB-366791 also led to an analgesic effect in the tail flick test. Tolerant mice that received SB-366791 demonstrated a central antinociceptive effect in both thermal tests. No genotoxic effects were observed in the comet assay and no mutagenic effects were detected in the micronucleus test or in the Salmonella/microsome assay. Behavioral results of the thermal nociception tests show that SB-366791 has antinociceptive potential in both morphine-tolerant and non-tolerant mice and does not cause genotoxic or mutagenic effects. Nevertheless, new studies should be performed to clarify the activity and participation of vanilloid channels in the antinociception of SB-366791.
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