The journal of pain : official journal of the American Pain Society
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Retraction Of Publication
The effect of intraoperative valdecoxib administration on PGE2 levels in the CSF.
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Comparative Study
Impact of postherpetic neuralgia and painful diabetic peripheral neuropathy on health care costs.
Knowledge of the health care costs associated with neuropathic pain is limited. Existing studies have not directly compared the health care costs of different neuropathic pain conditions, and patients with neuropathic pain have not been compared with control subjects with the same underlying conditions (for example, diabetes). To determine health care costs associated with postherpetic neuralgia (PHN) and painful diabetic peripheral neuropathy (DPN), patients with these conditions were selected from 2 different administrative databases of health care claims and respectively matched to control subjects who had a diagnosis of herpes zoster without persisting pain or a diagnosis of diabetes without neurological complications using propensity scores for demographic and clinical factors. Total excess health care costs attributable to PHN and painful DPN and excess costs for inpatient care, outpatient/professional services, and pharmacy expenses were calculated. The results indicated that the annual excess health care costs associated with peripheral neuropathic pain in patients of all ages range from approximately $1600 to $7000, depending on the specific pain condition. Total excess health care costs associated with painful DPN were substantially greater than those associated with PHN, which might reflect the great medical comorbidity associated with DPN. ⋯ The data demonstrate that the health care costs associated with 1 peripheral neuropathic pain condition cannot be extrapolated to other neuropathic pain conditions. The results also increase understanding of the economic burden of PHN and painful DPN and provide a basis for evaluating the impact on health care costs of new interventions for their treatment and prevention.
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This is a longitudinal predictive study to examine gender differences in the clinical correlates of risk for opioid misuse among chronic pain patients prescribed opioids for pain. Two hundred seventy-five male and 335 female patients prescribed opioids for chronic noncancer pain were asked to complete a series of baseline questionnaires, including the revised Screener and Opioid Assessment for Pain Patients (SOAPP-R). After 5 months, the subjects were administered a structured prescription drug use interview (Prescription Drug Use Questionnaire; PDUQ) and submitted a urine sample for toxicology assessment. Their treating physicians also completed a substance misuse behavior checklist (Prescription Opioid Therapy Questionnaire; POTQ). At 5-month follow-up, women showed higher scores on the PDUQ (P < .05), whereas men had a higher incidence of physician-rated aberrant drug behavior on the POTQ (P < .05). An item analysis of the SOAPP-R, PDUQ, and POTQ showed that women tended to score higher on items relating to psychological distress, whereas the male patients tended to report having more legal and behavioral problems. These results suggest that risk factors associated with prescription opioid misuse may differ between men and women. ⋯ Understanding gender differences in substance abuse risk among chronic pain patients is important for clinical assessment and treatment. This study suggests that women are at greater risk to misuse opioids because of emotional issues and affective distress, whereas men tend to misuse opioids because of legal and problematic behavioral issues.
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While occupational exposure to vibration is a common cause of acute and chronic musculoskeletal pain, eliminating exposure produces limited symptomatic improvement, and reexposure precipitates rapid recurrence or exacerbation. To evaluate mechanisms underlying these pain syndromes, we have developed a model in the rat, in which exposure to vibration (60-80Hz) induces, in skeletal muscle, both acute mechanical hyperalgesia as well as long-term changes characterized by enhanced hyperalgesia to a proinflammatory cytokine or reexposure to vibration. Exposure of a hind limb to vibration-produced mechanical hyperalgesia measured in the gastrocnemius muscle of the exposed hind limb, which persisted for approximately 2 weeks. When nociceptive thresholds had returned to baseline, exposure to a proinflammatory cytokine or reexposure to vibration produced markedly prolonged hyperalgesia. The chronic prolongation of vibration- and cytokine-hyperalgesia was prevented by spinal intrathecal injection of oligodeoxynucleotide (ODN) antisense to protein kinase Cepsilon, a second messenger in nociceptors implicated in the induction and maintenance of chronic pain. Vibration-induced hyperalgesia was inhibited by spinal intrathecal administration of ODN antisense to receptors for the type-1 tumor necrosis factor-alpha (TNFalpha) receptor. Finally, in TNFalpha-pretreated muscle, subsequent vibration-induced hyperalgesia was markedly prolonged. ⋯ These studies establish a model of vibration-induced acute and chronic musculoskeletal pain, and identify the proinflammatory cytokine TNFalpha and the second messenger protein kinase Cepsilon as targets against which therapies might be directed to prevent and/or treat this common and very debilitating chronic pain syndrome.
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Repeated injections of acidic saline into the gastrocnemius muscle induce both muscle and cutaneous hypersensitivity. We have previously shown that microinjection of local anesthetic into either the rostral ventromedial medulla (RVM) or the nucleus reticularis gigantocellularis (NGC) reverses this muscle and cutaneous hypersensitivity. Although prior studies show that NMDA receptors in the RVM play a clear role in mediating visceral and inflammatory hypersensitivity, the role of NMDA receptors in the NGC or in noninflammatory muscle pain is unclear. Therefore, the present study evaluated involvement of the NMDA receptors in the RVM and NGC in muscle and cutaneous hypersensitivity induced by repeated intramuscular injections of acidic saline. Repeated intramuscular injections of acidic saline, 5 days apart, resulted in a bilateral decrease in the withdrawal thresholds of the paw and muscle in all groups 24 hours after the second injection. Microinjection of NMDA receptor antagonists into the RVM reversed both the muscle and cutaneous hypersensitivity. However, microinjection of NMDA receptor antagonists into the NGC only reversed cutaneous but not muscle hypersensitivity. These results suggest that NMDA receptors in the RVM mediate both muscle and cutaneous hypersensitivity, but those in the NGC mediate only cutaneous hypersensitivity after muscle insult. ⋯ The current study shows that NMDA receptors in supraspinal facilitatory sites maintain noninflammatory muscle pain. Clinical studies in people with chronic widespread, noninflammatory pain, similarly, show alterations in central excitability. Thus, understanding mechanisms in an animal model could lead to improved treatment for patients with chronic muscle pain.