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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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.
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Clinical Trial
Fear of pain, pain catastrophizing, and acute pain perception: relative prediction and timing of assessment.
Pain-related fear and catastrophizing are important variables of consideration in an individual's pain experience. Methodological limitations of previous studies limit strong conclusions regarding these relationships. In this follow-up study, we examined the relationships between fear of pain, pain catastrophizing, and experimental pain perception. One hundred healthy volunteers completed the Fear of Pain Questionnaire (FPQ-III), Pain Catastrophizing Scale (PCS), and Coping Strategies Questionnaire-Catastrophizing scale (CSQ-CAT) before undergoing the cold pressor test (CPT). The CSQ-CAT and PCS were completed again after the CPT, with participants instructed to complete these measures based on their experience during the procedure. Measures of pain threshold, tolerance, and intensity were collected and served as dependent variables in separate regression models. Sex, pain catastrophizing, and pain-related fear were included as predictor variables. Results of regression analyses indicated that after controlling for sex, pain-related fear was a consistently stronger predictor of pain in comparison to catastrophizing. These results were consistent when separate measures (CSQ-CAT vs PCS) and time points (pretask vs "in vivo") of catastrophizing were used. These findings largely corroborate those from our previous study and are suggestive of the absolute and relative importance of pain-related fear in the experimental pain experience. ⋯ Although pain-related fear has received less attention in the experimental literature than pain catastrophizing, results of the current study are consistent with clinical reports highlighting this variable as an important aspect of the experience of pain.
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The current study sought to examine how changes in pain-related beliefs and coping responses are related to changes in pain interference and psychological functioning in individuals with spinal cord injuries (SCI) and pain. To measure longitudinal changes in these variables, respondents completed a survey that included measures of pain intensity, pain interference, and psychological functioning, as well as specific psychosocial variables (pain-related beliefs, coping, and social support) and then completed the same survey 6 months later; analyses included only the individuals who reported pain at both times (n = 40). Demographic and injury-related variables were also assessed, but none were found to be significantly associated with changes in functioning. Changes in catastrophizing and belief in one's ability to control pain were each significantly associated with changes in the outcome variables: Greater pain interference and poorer psychological functioning. Changes in specific coping strategies and social support were not predictors of changes in pain, interference, or psychological functioning. These findings support a biopsychosocial model of pain in persons with SCI. Intervention studies targeting maladaptive pain-related beliefs and catastrophizing may help to identify the causal nature of these relationships and may improve multidisciplinary treatment of pain in SCI. ⋯ Intervention studies targeting catastrophizing and maladaptive pain-related beliefs may be the next step in determining which variables play a causal role in the pain interference and psychological functioning of individuals with pain and SCI.