The journal of pain : official journal of the American Pain Society
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Chronic pain patients often report fears that movement will exacerbate their symptoms. The Tampa Scale of Kinesiophobia (TSK) was designed to assess fear of movement. Previous findings with the TSK showed inconsistent factor structures and varied measurement properties. The TSK was completed by a sample of 233 patients with fibromyalgia syndrome who were being evaluated for participation in a rehabilitation program. A principal components analysis initially derived a 5-factor solution. However, the factor structure accounted for less than 50% of the variance, and the internal consistency of the factors was below conventional standards (<0.70). A series of principal components analyses "forcing" different factor structures revealed that the best solution was a single factor solution that contained 4 of the original 17 TSK items, accounting for more than 50% of the variance with adequate internal consistency (alpha =0.71). Inspection of the content of these 4 items, however, suggests that this factor more likely represents catastrophic thinking, rather than fear of movement. Nevertheless, for patients with fibromyalgia syndrome, a 4-item TSK appears to retain the most acceptable factor solution while also maintaining adequate internal consistency. ⋯ Although the TSK is one of the most commonly used measures of fear of movement, the present study using the TSK with a sample of patients with fibromyalgia syndrome suggests that the measurement properties of the TSK are problematic. Recommendations for use of the TSK are provided.
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Randomized Controlled Trial Clinical Trial
Adding ultralow-dose naltrexone to oxycodone enhances and prolongs analgesia: a randomized, controlled trial of Oxytrex.
Oxytrex is a novel drug that combines oxycodone with ultralow-dose naltrexone, an opioid antagonist. Ultralow-dose opioid antagonists have been demonstrated to enhance and prolong opiate analgesia and alleviate opioid tolerance and withdrawal in rodents. This 3-week, Phase II clinical trial assessed safety and analgesic efficacy of Oxytrex in patients with moderate to severe pain from osteoarthritis. Patients with a pain score > or =5 received placebo, oxycodone 4 times a day (qid), Oxytrex qid, or Oxytrex twice a day (bid). All active treatment groups received the same total daily dose and dose escalation of oxycodone starting at 10 and ending at 40 mg/day. Importantly, the Oxytrex bid group received a lower daily dose of naltrexone than Oxytrex qid (0.002 vs 0.004 mg/day). Oxytrex bid produced a 39% reduction in pain intensity, which was significantly greater than that of placebo (P < .001), oxycodone qid (P = .006), and Oxytrex qid (P = .003). Oxytrex bid was also superior to placebo in quality of analgesia (P = .002), duration of pain control each day (P = .05), patients' global assessments (P = .04), and the Western Ontario and MacMaster Universities Osteoarthritis Index total score (P = .03). The incidence of side effects was comparable between active treatments. In this Phase II dose-ranging study, Oxytrex bid demonstrated greater pain relief with a more convenient dosing schedule compared to oxycodone qid. ⋯ Preclinical data have shown ultralow-dose opioid antagonists to enhance and prolong opioid analgesia while reducing analgesic tolerance and physical dependence. Recent molecular pharmacology data show a mechanism of action to be the prevention of aberrant G protein coupling by opioid receptors that underlies opioid tolerance and dependence.
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Temporal summation of deep tissue pain has been suggested to be facilitated in chronic musculoskeletal pain syndromes. This study aimed to test whether temporal summation of mechanical induced pressure pain is (1) more pronounced at short (1 second) interstimulus intervals (ISIs) compared with long ISI (30 seconds), (2) more potent than summation elicited by pure skin stimulation, and (3) attenuated in women compared with men. Twelve age-matched men and 12 women were included. A computer-controlled pressure stimulator with a probe surface of 1 cm2 was used to give 10 stimulations to the tibialis anterior, tibia periosteum, and the first web of the hand. Sequential stimulation at pressure pain threshold intensity was applied with different ISIs (1, 3, 5, 10, and 30 seconds). The pain intensity was assessed on a visual analog scale (VAS) after each individual stimulus. The VAS scores after the 10th stimulation with 1-second ISI were increased (P < .05) by 418% +/- 77%, 378% +/- 89%, and 234% +/- 66% compared with the first stimulation for tibia, tibialis anterior, and web, respectively. Temporal summation of pain was observed for all ISIs in tibialis anterior and tibia, eg, 30-second ISI evoked a VAS increase of 192% +/- 71 % (tibia) and 117% +/- 42% (tibialis anterior) compared with the first stimulation. The VAS score after the 10th web stimulation was smaller (P < .05) than that of the 10th tibialis anterior or tibia stimulation. A regression analysis between stimulation number and VAS score showed that the pain intensity increased progressively (1) more for 1-second ISIs compared with longer ISIs (P < .01) and (2) faster in deep tissue compared with skin (P < .01). No gender difference was observed. The temporal summation might be related to both central and peripheral mechanisms. ⋯ Pain originating in deep tissue influences central pain processing systems more than superficial tissue. This might be of importance in patients with musculoskeletal pain.
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The Medication Quantification Scale (MQS) is an instrument with potential clinical and research applications for quantifying medication regimen use in chronic pain populations. The MQS was developed in 1992 and updated in 1998 (MQS II) as a tool to co-quantify 3 relevant aspects of medications prescribed for chronic nonmalignant pain: drug class, dosage, and detriment (risk). This 2003 version (MQS III) is the third iteration of the scale, featuring new detriment weights determined by surveying all physician members of the American Pain Society in the United States via mail. A total of 248 physicians (18%) responded with their opinion as to the detriment of 22 mechanistically distinct medication classes. Overall, the physician ratings of detriment weight were relatively consistent (alpha = .84). The increased number of survey responses encompassed a wide range of disciplines, thus reducing discipline bias and introducing several important changes to MQS scoring. Some medication classes previously rated with low detriment weights (eg, nonsteroidal anti-inflammatory drugs) increased in detriment weight (from 2 to 3.4), whereas other classes previously given high weights (eg, "strong" opioids) received lower detriment ratings (from 5 to 3.4) in this survey. The MQS III must now be validated in clinical and research applications. ⋯ The MQS is a tool to objectively quantify pain. It computes a single numeric value for a patient's pain medication profile. This number can be used by both clinicians and researchers to track pain levels through a treatment course or research study.
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Heart rate (HR) is currently used by rehabilitation clinicians as a complementary objective measure of pain. The premise is that, as pain increases, HR should also increase. However, this relationship is not clearly established. The goal of this study was to verify the relationship between HR and pain perception. Thirty-nine healthy volunteers participated in this experimental study. Painful stimuli were induced by a 2-minute immersion of the hand in hot water (47 degrees C). HR was recorded before and during the stimulation and was matched to a pain rating. We observed a rise of 11% in HR after 2 minutes of immersion. There was a significant intrasubject correlation between HR and pain intensity (r = 0.50, P < .001) and pain unpleasantness (r = 0.55, P < .001). Furthermore, there was a strong gender effect in the intersubject correlations. Men presented a strong correlation between mean HR and mean pain perception (intensity: r = 0.77, unpleasantness: r = 0.86), whereas this relationship was absent in women (intensity: r = -0.2, unpleasantness: r = 0.001). In conclusion, results show that, for healthy volunteers, experimental pain can elicit a rise in HR up to 11%. Moreover, the relationship between HR response and pain is gender related. Considering that a positive relationship between HR and pain perception was only found in men, these results do not support a clinical significance of the use of HR for pain evaluation in women. Clinical implications need to be further evaluated with patients before clinicians can use HR as a complementary tool in pain assessment. ⋯ A positive correlation between HR and pain was observed for men but not for women. These differences underline the importance of taking into account gender differences in the development of complementary pain assessment. Further research should be conducted to verify the role of sex hormones on heart rate and pain.