The journal of pain : official journal of the American Pain Society
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Randomized Controlled Trial
A randomized, controlled trial of oxycodone versus placebo in patients with postherpetic neuralgia and painful diabetic neuropathy treated with pregabalin.
The aim of this randomized double-blind, placebo-controlled, parallel-group study was to evaluate the efficacy, safety, and tolerability of pregabalin in combination with oxycodone or placebo, in patients with either postherpetic neuralgia (PHN) or painful diabetic neuropathy (PDN). After a 7-day washout period, 62 patients were randomized to receive either oxycodone mixture 10 mg/day or placebo mixture for 1 week. Patients were then started on open-label pregabalin (75, 150, 300 and 600 mg/day) according to a forced titration dosing regimen, while continuing the same dosage of oxycodone or placebo for 4 weeks. The primary efficacy measure was a decrease in the pain-intensity score of at least 2cm and a pain score <4cm measured using a 10-cm visual analogue scale (VAS) following pregabalin dosage escalation and treatment for 4 weeks. Secondary efficacy measures included sleep interference and the Neuropathic Pain Scale. There were similar levels of overall efficacy between pregabalin/oxycodone and pregabalin/placebo groups in relieving PHN and PDN related pain. ⋯ Peripheral neuropathic pain presents commonly in clinical practice, and 2 of its most prevalent types are PHN and PDN. Currently available treatments provide some degree of pain relief in approximately 40-60% of patients, leaving the remainder with unremitting pain. Although this study supports the effectiveness of pregabalin in the treatment of PHN or PDN, it also shows that the addition of a low dose of oxycodone at 10mg/day does not enhance the pain-relieving effects of pregabalin.
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The Douleur Neuropathique 4 (DN4) questionnaire was developed by the French Neuropathic Pain Group and is a simple and objective tool, with the ability to distinguish nociceptive from neuropathic pain. The purpose of this work was to validate the DN4 questionnaire in the Portuguese language in order to allow its use in clinical and research settings. A double-blind, accuracy study was conducted, consisting of translation, back-translation, literal evaluation, semantic equivalence, and communication with the target population. The Portuguese version of the questionnaire was applied in a sample of 101 patients with neuropathic (N = 42) or nociceptive pain (N = 59), ranked according to medical diagnosis. The reproducibility, reliability and validity of the instrument were analyzed, and showed a high diagnostic power for this version of the DN4 questionnaire. The Portuguese version of the DN4 questionnaire presented good validity and reliability, allowing it to identify neuropathic pain and neuropathic characteristics of mixed pain syndromes. ⋯ This article presents the first validated neuropathic pain questionnaire in the Portuguese language and represents a useful tool in the assessment of neuropathic pain both in the clinical setting and in population-based studies. The sensible and quick format of this instrument are key factors that will contribute to its widespread use, permitting a true recognition of patients with neuropathic pain.
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Altered function of endogenous pain modulation has been proposed as a mechanism that may underlie chronic pain conditions. Descending modulation of pain can be examined by diffuse noxious inhibitory controls (DNIC). DNIC comprises a spinal-medullary-spinal pathway that is activated when 2 concomitant painful stimuli are applied at the same time. This pain-inhibitory system can be easily triggered in an experimental setting. Therefore, studies on DNIC can help us to evaluate impairments in descending pain modulation, presumably primarily of inhibitory nature. This review summarizes recent findings on human DNIC trials with a specific focus on sex, age, and ethnic differences in DNIC effects and psychological mediators such as attention, expectation, and pain catastrophizing. Furthermore, the clinical relevance of DNIC studies will be discussed. Different methodological approaches used make it difficult to generalize results, but the research to date has shown good potential for DNIC to help in gaining insights in the underlying mechanisms of chronic pain conditions. ⋯ Recent literature on diffuse noxious inhibitory controls as a model of endogenous pain modulation in clinical pain syndromes was reviewed. DNIC may help to identify patients at risk for development of chronic pain and may open alternatives for treatment options.
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Research generally indicates that providers demonstrate modest insight into their clinical decision processes. In a previous study utilizing virtual human (VH) technology, we found that patient demographic characteristics and facial expressions of pain were statistically significant predictors of many nurses' pain-related decisions. The current study examined the correspondence between the statistically identified and self-reported influences of contextual information on pain-related decisions. Fifty-four nurses viewed vignettes containing a video of a VH patient and text describing a postsurgical context. VH sex, race, age, and facial expression varied across vignettes. Participants made pain-assessment and treatment decisions on visual analogue scales. Participants subsequently indicated the information they relied on when making decisions. None of the participants reported using VH sex, race, or age in their decision process. Statistical modeling indicated that 28 to 54% of participants (depending on the decision) used VH demographic cues. 76% of participants demonstrated concordance between their reported and actual use of the VH facial expression cue. Vital signs, text-based clinical summary, and VH movement were also reported as influential factors. These data suggest that biases may be prominent in practitioner decision-making about pain, but that providers have minimal awareness of and/or a lack of willingness to acknowledge this bias. ⋯ The current study highlights the complexity of provider decision-making about pain management. The VH technology could be used in future research and education applications aimed at improving the care of all persons in pain.
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Catastrophizing is widely recognized as an important risk factor for adverse pain-related outcomes. However, questions remain surrounding the details of its assessment. In particular, recent laboratory studies suggest that evaluation of "situational" catastrophizing (ie, catastrophizing measured during or directly after the administration of noxious stimulation) may provide information distinct from that obtained by standard, or "dispositional" measures, which assess individuals' recall of catastrophizing in daily life. However, comparatively little research has systematically investigated the interrelationships and properties of these 2 different forms of pain-related catastrophizing. The current study evaluated both situational and dispositional catastrophizing measures within multiple samples: healthy individuals (N = 84), patients with painful temporomandibular joint disorders (TMD; N = 48), and patients with painful arthritis (N = 43). All participants first completed the Pain Catastrophizing Scale (PCS), and then underwent psychophysical pain testing, which included heat, cold, and pressure pain. Participants then completed a situational catastrophizing measure with reference to the laboratory pain he/she had just undergone. Situational catastrophizing scores were not significantly correlated with dispositional PCS scores in the healthy participants and arthritis patients, though they were associated in TMD patients. Situational catastrophizing was more strongly associated with experimental pain responses than dispositional PCS scores for the healthy subjects and arthritis patients. In general, higher levels of situational catastrophizing were associated with lower pain thresholds and higher pain ratings across all 3 samples. The findings highlight the importance of multidimensional assessment of pain-related catastrophizing, and suggests a role for measuring catastrophizing related to specific, definable events. ⋯ This study adds to a growing literature examining catastrophizing. Our findings highlight the potential importance of the multidimensional assessment of pain-related catastrophizing, and suggest a role for measuring catastrophizing related to specific, definable events.