The journal of pain : official journal of the American Pain Society
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Clinical Trial
Ethnic differences in pain perception and patient-controlled analgesia usage for postoperative pain.
There are reports suggesting that sensitivity to and tolerance of both clinical and experimental pain differ among ethnic groups. We examined self-rated pain score and morphine usage in 1034 women who underwent elective lower cesarian section (LSCS) for their deliveries. Data on pain scores and amount of total morphine use according to patient-controlled analgesia were collected every 4 hours. Overall, lowest pain scores were recorded 12 hours after surgery and highest at 24 hours. Morphine consumption was highest within the first 4 hours and lowest between 12 and 16 hours. There were statistically significant ethnic group differences in pain scores (P = 1.7 x 10(-7)) and morphine usage (P = 2.8 x 10(-15)) between ethnic groups, with Indians having the highest mean pain score and using the highest amount of morphine. The ethnic differences in pain score and morphine self-administration persisted after controlling for age, body mass index, and duration of operation. ⋯ Our findings of highly significant ethnic group difference in self-reported pain level and the amount of analgesia self-administered may have implications on optimal management of acute postoperative pain. Inadequate management of pain after cesarian deliveries might affect the emotional well-being and physical recovery of patients and affect mother-child bonding.
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Chronic pain after breast cancer surgery is a major problem and is expected to increase in the coming years because of an increased prevalence of breast cancer coupled with better survival. Axillary lymph node dissection (ALND) in patients with breast cancer is associated with nerve damage. The present study investigated the effect of ALND on the prevalence and intensity of chronic pain after breast cancer surgery. Furthermore, we studied the effect of chemotherapy and radiotherapy on chronic pain and the quality of life after breast cancer surgery. We analyzed 317 questionnaires of patients who underwent surgery for breast cancer between 2002 and 2004. In the first part, questions were asked concerning the prevalence of chronic pain, its intensity (visual analog scale), and phantom breast pain. The second part covered quality of life and included the EORTC QLQ-C30/BR-23. The prevalence of chronic pain after breast cancer surgery with ALND is double that without ALND (51% vs 23%). Chronic pain intensity and prevalence of phantom breast pain were not influenced by ALND. Chemotherapy and radiotherapy in interaction with ALND were associated with increased prevalence of chronic pain. The quality of life in patients was mainly affected by chronic pain and to a lesser extent by type of surgery. ⋯ Nerve injury is particularly efficient at producing central sensitization. ALND in conjunction with breast cancer surgery is associated with a doubled prevalence of chronic pain, which has not been described to date. ALND and nerve injury may play a major role in pain chronification after breast cancer surgery.
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Our group previously demonstrated that changes in mood induced by pleasant or unpleasant odors affect the perceived unpleasantness of painful heat stimuli, without significantly altering perceived pain intensity. In the present study, we examined whether changing mood by viewing emotionally laden visual stimuli also preferentially alters pain unpleasantness. Twelve female subjects immersed their right hand in hot water while observing a video showing a person experiencing the same type of pain (ie, model condition), unpleasant scenes not involving people (ie, disasters condition), or a cityscape video (ie, cityscape condition). Subjects were asked to rate pain intensity, pain unpleasantness, mood, anxiety/calmness, and video unpleasantness, and their skin conductance was measured throughout the experiment. Pain unpleasantness (but not intensity) ratings were higher during the disasters condition, which was associated with the worst mood, than during the cityscape condition; neither mood nor pain unpleasantness was altered in the model video compared with the cityscape video. Moreover, mood was significantly correlated with pain unpleasantness but not with pain intensity. Because these results are similar to those observed when odors were used to alter mood, we conclude that the effects of mood on the affective components of pain are independent of mood induction technique used. ⋯ This article provides new evidence that changes in mood affect the pain experience by preferentially modulating pain unpleasantness. This finding could potentially help health professionals to treat pain symptoms in patients with altered mood, suggesting methods of pain management aimed at easing the affective, along with the sensory, components of pain.
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Randomized Controlled Trial Multicenter Study
A 14-week, randomized, double-blinded, placebo-controlled monotherapy trial of pregabalin in patients with fibromyalgia.
The purpose of the study was to assess the efficacy and safety of pregabalin monotherapy in patients with fibromyalgia in a randomized, double-blinded, placebo-controlled trial. After 1 week of single-blinded administration of placebo, 750 patients meeting American College of Rheumatology criteria for fibromyalgia were randomly assigned to pregabalin (300 mg/d, 450 mg/d, 600 mg/d) or placebo, administered twice daily for 14 weeks. The primary outcome variable was comparison of end point mean pain scores, derived from daily diary ratings of pain intensity (0 to 10 scale), between each of the pregabalin groups and the placebo group. If positive, additional primary efficacy parameters included the Patient Global Impression of Change (PGIC) and the Fibromyalgia Impact Questionnaire (FIQ) total score. Compared with placebo-treated patients, mean changes in pain scores at the end point in pregabalin-treated patients were significantly greater (P < .001: 300 mg/d, -0.71; 450 mg/d, -0.98; 600 mg/d, -1.00). Compared with placebo, significantly more pregabalin-treated patients reported improvement on PGIC (P < .01 for all 3 pregabalin doses) and significant improvements in total FIQ score for the 450 mg/d (P = .004) and the 600 mg/d (P = .003) doses. Compared with placebo, all 3 doses of pregabalin were associated with significant improvement in sleep. The most commonly reported pregabalin-related adverse events were dizziness and somnolence, which tended to be dose-related. ⋯ This randomized, placebo-controlled trial of 300, 450, and 600 mg/d of pregabalin monotherapy demonstrated that all 3 doses were efficacious for up to 14 weeks for the treatment of fibromyalgia and were well tolerated by most patients. These results provide evidence that pregabalin is an important treatment option for patients with fibromyalgia.
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Randomized Controlled Trial
Acute opioid administration improves work-related exercise performance in patients with chronic back pain.
We studied the impact of acute opioid administration on work-related exercise performance in patients with chronic back pain. A double-blinded, random-order, placebo-controlled, crossover trial was conducted. Subjects were predominantly men (63%), with a mean age of 49 years. Subjects performed a continuous lifting and lowering test to voluntary fatigue at a load equivalent to 33% of their predetermined maximal lifting load twice: Once after receiving a single intravenous dose of 1 mug/kg fentanyl (a narcotic analgesic) and once after saline placebo. Of the 30 subjects undergoing testing, 3 subjects were unable to complete testing due to medication-induced nausea. Subjects lifted on average 29.4 +/- 17.9 kg under the influence of fentanyl versus 25.6 +/- 3.1 kg with placebo (effect size = 0.23). Time to fatigue was higher in the fentanyl group (312 +/- 251.4 vs 231 +/- 199.9 seconds, effect size = 0.40), and these subjects also performed more total work (7004 +/- 5144 vs 4748 +/- 3147 J, effect size = 0.72). Opioid analgesia improves lifting performance in the short term in individuals with chronic back pain. Longer trials of the effectiveness of opioid analgesia as an adjunct to functional restoration programs are recommended. ⋯ This article presents the results of a clinical trial showing that acute opioid administration improves work-related exercise performance in individuals with chronic back pain. Longer trials of the effectiveness of opioid analgesia as an adjunct to functional restoration programs are recommended.