Pain
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Meta Analysis
A meta-analysis of the analgesic effects of omega-3 polyunsaturated fatty acid supplementation for inflammatory joint pain.
Between 40% and 60% of Americans use complementary and alternative medicine to manage medical conditions, prevent disease, and promote health and well-being. Omega-3 polyunsaturated fatty acids (omega-3 PUFAs) have been used to treat joint pain associated with several inflammatory conditions. We conducted a meta-analysis of 17 randomized, controlled trials assessing the pain relieving effects of omega-3 PUFAs in patients with rheumatoid arthritis or joint pain secondary to inflammatory bowel disease and dysmenorrhea. ⋯ Supplementation with omega-3 PUFAs for 3-4 months reduces patient reported joint pain intensity (SMD: -0.26; 95% CI: -0.49 to -0.03, p=0.03), minutes of morning stiffness (SMD: -0.43; 95% CI: -0.72 to -0.15, p=0.003), number of painful and/or tender joints (SMD: -0.29; 95% CI: -0.48 to -0.10, p=0.003), and NSAID consumption (SMD: -0.40; 95% CI: -0.72 to -0.08, p=0.01). Significant effects were not detected for physician assessed pain (SMD: -0.14; 95% CI: -0.49 to 0.22, p=0.45) or Ritchie articular index (SMD: 0.15; 95% CI: -0.19 to 0.49, p=0.40) at 3-4 months. The results suggest that omega-3 PUFAs are an attractive adjunctive treatment for joint pain associated with rheumatoid arthritis, inflammatory bowel disease, and dysmenorrhea.
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Temporal summation of "second pain" (TSSP) is considered to be the result of C-fiber-evoked responses of dorsal horn neurons, termed 'windup'. This phenomenon is dependent on stimulus frequency (0.33 Hz) and relevant for central sensitization and chronic pain. Previous brain imaging studies have only been used to characterize neural correlates of second pain but not its temporal summation. ⋯ As predicted, experimental pain ratings showed robust TSSP during 0.33 Hz but not 0.17 Hz stimuli. fMRI statistical maps identified several brain regions with stimulus and frequency dependent activation consistent with TSSP, including contralateral thalamus (THAL), S1, bilateral S2, anterior and posterior insula (INS), mid-anterior cingulate cortex (ACC), and supplemental motor areas (SMA). TSSP ratings were significantly correlated with brain activation in somatosensory areas (THAL, S1, left S2), anterior INS, and ACC. These results show that neural responses related to TSSP are evoked in somatosensory processing areas (THAL, S2), as well as in multiple areas that serve other functions related to pain, such as cognition (ACC, PFC), affect (INS, ACC, PAG), pre-motor activity (SMA, cerebellum), and pain modulation (rostral ACC).
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Pain that interferes with daily life appears to be strongly age-related in cross-sectional studies, although the nature of this relationship over time has not been established. We have investigated the onset and persistence of pain and pain interference over a 3-year period to determine their association with age in older people. A 3-year follow-up postal survey was conducted of adults aged 50 years and over (n=5366) who had previously been recruited as part of the North Staffordshire Osteoarthritis Project. ⋯ In adults aged 50 years and over, the onset of pain that interferes with life shows a clear gender difference and a consistent rise with age into the oldest age-group. This was in strong contrast to the onset of pain which showed no gender or age-related trends. The implications for public health, as for the treatment of the individual, are twofold, relating to efforts to prevent disabling pain from occurring and to understand the factors that accelerate the impact which pain has on everyday life when people reach the oldest ages.
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Previously, we demonstrated, in a randomized clinical trial, the effectiveness of a psychoeducational intervention to decrease pain intensity scores and increase patients' knowledge of cancer pain management with a sample of oncology patients with pain from bone metastasis. In the present study, we evaluated for changes in mood states (measured using the Profile of Mood States), quality of life (QOL; measured using the Medical Outcomes Study Short Form-36 (SF-36)), and pain's level of interference with function (measured using the Brief Pain Inventory (BPI)) from baseline to the end of the intervention first between the intervention and the standard care groups and then within the intervention group based on the patients' level of response to the intervention (i.e., patients were classified as non-responders, partial responders, or responders). ⋯ Differences in the physical and mental component summary scores on the SF-36 and the interference items on the BPI, among the three respondent groups, were not only statistically significant but also clinically significant. The use of responder analysis in analgesic trials may help to identify unique subgroups of patients and lead to the development of more effective psychoeducational interventions.
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Clinical Trial
Ethnic identity predicts experimental pain sensitivity in African Americans and Hispanics.
The aim of this study was to examine experimental pain sensitivity in three ethnic groups, African Americans, Hispanic Americans and non-Hispanic White Americans, and to determine whether ethnic identity is differentially associated with pain sensitivity across ethnic groups. Participants included sixty-three African American, sixty-one Hispanic and eighty-two non-Hispanic white participants who were assessed using three experimental pain measures: thermal, cold-pressor and ischemic. Participants' ethnic identity was assessed using the Multi-group Ethnic Identity Measure (MEIM). ⋯ Statistically controlling for ethnic identity rendered some of the group differences in pain range non-significant. These findings indicate that ethnic identity is associated with pain sensitivity in ethnic minority groups, and may partially mediate group differences in pain perception. The results of the present investigation provide evidence of ethnic group differences in responses to experimental pain across multiple noxious stimuli, with both minority groups exhibiting greater sensitivity to laboratory evoked pain compared to non-Hispanic White Americans.