The journal of pain : official journal of the American Pain Society
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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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Retraction Of Publication
Perioperative perineural infusion of bupivacaine and clonidine following lower extremity amputation.
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Randomized Controlled Trial Multicenter Study
Feasibility study of Transcutaneous Electrical Nerve Stimulation (TENS) for cancer bone pain.
This multicenter study assessed the feasibility of conducting a phase III trial of transcutaneous electrical nerve stimulation (TENS) in patients with cancer bone pain recruited from palliative care services. Eligible patients received active and placebo TENS for 1 hour at site of pain in a randomized crossover design; median interval between applications 3 days. Responses assessed at 30 and 60 minutes included numerical and verbal ratings of pain at rest and on movement, and pain relief. Recruitment, tolerability, adverse events, and effectiveness of blinding were also evaluated. Twenty-four patients were randomised and 19 completed both applications. The intervention was well tolerated. Five patients withdrew: 3 due to deteriorating performance status, and 2 due to increased pain (1 each following active and placebo TENS). Confidence interval estimation around the differences in outcomes between active and placebo TENS suggests that TENS has the potential to decrease pain on movement more than pain on rest. Nine patients did not consider that a placebo was used; the remaining 10 correctly identified placebo TENS. Feasibility studies are important in palliative care prior to undertaking clinical trials. Our findings suggest that further work is required on recruitment strategies and refining the control arm before evaluating TENS in cancer bone pain. ⋯ Cancer bone pain is common and severe, and partly mediated by hyperexcitability. Animal studies suggest that Transcutaneous Electrical Nerve Stimulation can reduce hyperalgesia. This study examined the feasibility of evaluating TENS in patients with cancer bone pain in order to optimize methods before a phase III trial.
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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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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.