The journal of pain : official journal of the American Pain Society
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Obesity contributes to several chronic pain conditions, negatively affecting quality of life (QOL). However, obesity's relationship with chronic pain is poorly understood. This prospective survey study examines obesity's role in chronic pain and subsequent impact on QOL. Black and white patients with chronic pain (N = 183, 18-50 years of age, 64% women, 50% black) were studied to determine predictors for the presence of body mass index (BMI) information in medical records, group BMI differences, and how BMI and pain contribute to mental/physical outcomes. BMI was calculated by using medical records nearest the enrollment date. Sociodemographic data, sleep, pain, functioning, disability, and depression were measured. BMI data were available for 143 subjects (78%), with blacks having a higher BMI (P = .002). Black (P = .08), people with higher pain (P < .01), affective distress (P < .01), and post-traumatic stress disorder scores (P = .07) were less likely to have their BMI recorded. Path analysis tested relationships between sociodemographics, BMI and pain with functioning, depression, and disability. BMI was positively associated with black race and age and predicted poorer physical functioning and greater disability. Pain was not predicted by race or age but was associated with all outcomes. These findings support assessing BMI when managing chronic pain and its negative impact on QOL, especially for minority patients. ⋯ This study examines the relationships among sociodemographic factors, BMI, and QOL in chronic pain. Our results demonstrate significant racial disparity among chronic pain patients in assessing BMI and quality of pain care. These findings support obesity's negative impact on overall health and the importance of measuring BMI in patients with chronic pain, especially racial and ethnic minorities.
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Current fear-anxiety-avoidance models of chronic pain emphasize pain-related fear and anxiety as potential precursors for disabling chronic pain; however, anxiety and fear are often used interchangeably when discussing pain. Fear is a present-oriented emotive state associated with an imminent threat (eg, a patient about to receive an injection), whereas anxiety is a more general, future-oriented emotive state, that occurs in anticipation of threats without requiring an objective stimulus (eg, the possibility of receiving an injection). Theoretical and empirical evidence suggests pain-related fear and anxiety represent distinct cognitive constructs. Moreover, pain-related anxiety has been posited as a manifestation of anxiety sensitivity, which has implications for several theoretical models as well as treatment. The Fear of Pain Questionnaire and the Pain Anxiety Symptoms Scale-20 are popular measures, often used comparably, that were designed to measure pain-related fear and anxiety, respectively. These measures, along with the Anxiety Sensitivity Index, were administered to an undergraduate sample (N = 268; 66% women). Results of confirmatory factor analyses suggest each measure represents a related, but distinct, construct. Furthermore, correlations with anxiety sensitivity suggest that pain-related anxiety may be better conceptualized as a fundamental fear. Implications and directions for future research are discussed. ⋯ Fear-anxiety-avoidance models of chronic pain posit pain-related fear and anxiety as diatheses for disabling chronic pain. This research suggests theoretical and clinical distinctions between pain-related fear and anxiety. Moreover, pain-related anxiety appears more complex than a manifestation of anxiety sensitivity; pain-related anxiety may be better conceptualized as a fundamental fear.
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Inflammatory cytokines contribute to lumbar radiculopathy. Regulation of cytokines for transient cervical injuries, with or without longer-lasting inflammation, remains to be defined. The C7 root in the rat underwent compression (10gf), chromic gut suture exposure (chr), or their combination (10gf+chr). Ipsilateral C7 spinal cord and dorsal root ganglia (DRG) were harvested at 1 hour after injury for real-time PCR analysis of IL-1beta, IL-6, and TNF-alpha. Cytokine mRNA increased after all 3 injuries. TNF-alpha mRNA in the DRG was significantly increased over sham after 10gf+chr (P = .026). Spinal IL-1beta was significantly increased over sham after 10gf and 10gf+chr (P < .024); IL-6 was significantly increased after 10gf+chr (P < .024). In separate studies, the soluble TNF-alpha receptor was administered at injury and again at 6 hours in all injury paradigms. Allodynia was assessed and tissue samples were harvested for cytokine PCR. Allodynia significantly decreased with receptor administration for 10gf and 10gf+chr (P < .005). Treatment also significantly decreased IL-1beta and TNF-alpha mRNA in the DRG for 10gf+chr (P < .028) at day 1. Results indicate an acute, robust cytokine response in cervical nerve root injury with varying patterns, dependent on injury type, and that early increases in TNF-alpha mRNA in the DRG may drive pain-related signaling for transient cervical injuries. ⋯ Inflammatory cytokine mRNA in the DRG and spinal cord are defined after painful cervical nerve root injury. Studies describe a role for TNF-alpha in mediating behavioral sensitivity and inflammatory cytokines in transient painful radiculopathy. Results outline an early response of inflammatory cytokine upregulation in cervical pain.
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Randomized Controlled Trial Comparative Study
Effect of morphine and pregabalin compared with diphenhydramine hydrochloride and placebo on hyperalgesia and allodynia induced by intradermal capsaicin in healthy male subjects.
Intradermal (ID) capsaicin injection in humans induces spontaneous pain, flare, primary hyperalgesia, secondary hyperalgesia, and allodynia. Secondary hyperalgesia and allodynia are a reflection of central sensitization. The effect of treatment of single doses of (1) pregabalin, 300 mg single oral dose, and (2) morphine, 10 mg IV, on the area of secondary hyperalgesia induced by ID capsaicin injection was studied by using a randomized, double-blinded, placebo-controlled, 4-period, cross-over design in 20 healthy men. Compared with active placebo diphenhydramine (50 mg oral dose), pregabalin and morphine significantly reduced the area of secondary hyperalgesia over 15 to 240 minutes after capsaicin injection (approximately 25%, P = .002 and approximately 33%, P < .001, respectively). A smaller reduction was observed when pregabalin and morphine were compared with true placebo (approximately 13%, P = .081 and approximately 24%, P = .009, respectively). Diphenhydramine, on the other hand, increased the area of secondary hyperalgesia in comparison with true placebo (approximately 16%, P = .061). The relationship between the baseline area of hyperalgesia and assay sensitivity suggests that establishing minimum entry criteria for the baseline area of hyperalgesia requirement increases the sensitivity of the assay. ⋯ These results suggest that the minimally invasive intradermal capsaicin model, when it is compared with true placebo, can potentially be used for an early assessment of relevant pharmacology of novel analgesic compounds in healthy subjects. This platform may provide a means to rapidly assess new analgesics and enhance dose selection and decision-making during clinical development.
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Multicenter Study
Validating PRISM (Pictorial Representation of Illness and Self Measure) as a measure of suffering in chronic non-cancer pain patients.
The Pictorial Representation of Illness and Self Measure (PRISM) is a recently developed tool designed to measure the burden of suffering due to illness in a variety of patient populations. The purpose of the current study was to validate PRISM as a measure of suffering in patients with chronic non-cancer pain. Patients (n = 138) were recruited from 2 hospital pain clinics, where they were participating in a 10-week, mindfulness-based chronic pain management course and during which they completed validated questionnaires to assess their outcomes. Convergent validity was assessed by correlating their PRISM scores with scores on the Short-Form 36v2 quality of life instrument, the Pain Catastrophizing Scale, and the 0 to 10 Numeric Pain Scale. Content validity and test-retest reliability were assessed, and a factor analysis performed to identify relationships among the PRISM domains. PRISM was found to have good reliability and was significantly correlated with many of the subdomains of the other questionnaires. Qualitative data (n = 26) revealed that PRISM was well understood and that there was consistency in interpreting the task. Our data suggest that the PRISM task measures constructs relating to quality of life, pain catastrophizing, and pain intensity and probably measures suffering in patients with chronic non-cancer pain, providing a novel and quick tool for clinicians. ⋯ This study demonstrates the reliability and validity of the PRISM task for measuring the burden of pain in a population of chronic pain sufferers. Clinicians in the field of chronic pain management may find PRISM useful for monitoring the impact of pain management strategies on pain perception and the psychosocial variables that influence suffering.