Pain
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Randomized Controlled Trial Multicenter Study
How do changes in pain severity levels correspond to changes in health status and function in patients with painful diabetic peripheral neuropathy?
The current analysis compares changes in pain with changes in function and health status in individuals with painful diabetic peripheral neuropathy (DPN). The post hoc analysis is based on a 12week, multinational, placebo-controlled trial of pregabalin in which 401 patients were randomized to treatment. Study measures included the Brief Pain Inventory short-form (BPI-sf), EQ-5D and other patient-reported outcomes. ⋯ Similarly, a reduction in the NRS of 30% and 50% corresponded to a 3-point and a 5-point improvement in the PII, respectively. Changes in pain were also associated with changes in health status. Results suggest that patients whose pain is not reduced to a mild level of severity can still experience clinically important changes in function and health status.
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Due to the cross-sectional nature of previous studies, whether mechanical factors predict the onset of Chronic oro-facial pain remains unclear. Aims of the current study were to test the hypotheses that self-reported mechanical factors would predict onset of Chronic oro-facial pain and that any observed relationship would be independent of the confounding effects of psychosocial factors and reporting of other unexplained symptoms. About 1735 subjects who had completed a baseline questionnaire were assessed at 2year follow-up for the presence of Chronic oro-facial pain, psychosocial factors (anxiety and depression, illness behaviour, life stressors and reporting of somatic symptoms), mechanical dysfunction (facial trauma, grinding, phantom bite and missing teeth) and reporting of other unexplained symptoms (chronic widespread pain, irritable bowel syndrome and chronic fatigue). ⋯ I. 2.2-7.4) and age (RR 0.2, 95% CI 0.1-0.7). The findings from this prospective study support the hypothesis that psychosocial factors are markers for onset of Chronic oro-facial pain. The efficacy of early psychological management of Chronic oro-facial pain to address these factors should be a priority for future investigations.
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The ethics of placebo research have been of paramount concern since the discovery of the phenomenon. To address these ethical concerns, Miller and colleagues (PLoS Med 2005 Sep;2(9):e262, 0853-0859) propose an alternate approach to placebo research, called "authorized deception", in which participants are alerted of the use of deception in the research prior to study enrollment and thus knowingly permit its use if they decide to participate. The present study sought to investigate the authorized deception methodology in experimentally induced placebo analgesia. ⋯ The majority of participants who received this form of consent preferred it to the traditional approach in which the participants are not alerted to the presence of deception. These findings suggest that the use of authorized deception is a viable and ethically preferable alternative consent process for laboratory-based studies on placebo analgesia. Further studies are needed to examine the effect of authorized deception in clinical trials and other placebo research within a clinical setting.
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In the present study, intraplantar carrageenan induced increased mechanical allodynia, phosphorylation of PKB/Akt and GluR1 ser 845 (PKA site) as well as GluR1, but not GluR2 movement into neuronal membranes. This change in membrane GluR1/GluR2 ratio is indicative of Ca(2+) permeable AMPA receptor insertion. Pain behavior was reduced and biochemical changes blocked by spinal pretreatment, but not post-treatment, with a tumor necrosis factor (TNF) antagonist, Etanercept (100microg). ⋯ Akt and GluR1 phosphorylation, AMPA receptor trafficking and mechanical allodynia were all TNF dependent. Whether phosphorylation of Akt and of GluR1 are in series or in parallel or upstream of pain behavior remains to be determined. Certainly, TNF-mediated GluR1 trafficking appears to play a major role in inflammatory pain and TNF-mediated effects such as these could represent a path by which glia contribute to neuronal sensitization (spinal LTP) and pathological pain.