The journal of pain : official journal of the American Pain Society
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Pain is a serious consequence of spinal cord injury (SCI). Our aim was to investigate the temporal aspects of different types of pain following traumatic SCI and to determine possible predictors of neuropathic pain. Prospective data on 90 patients were collected at 1, 6, and 12 months after traumatic SCI. The patients completed questionnaires on pain severity, descriptors, and impact and underwent clinical examination with bedside sensory testing. Eighty-eight patients completed the 12-month follow-up. Approximately 80% of patients reported any type of pain at all 3 time points. Neuropathic pain related to SCI increased over time, and musculoskeletal pain decreased slightly, with both being present in 59% of patients at 12 months; other neuropathic pain not related to SCI and visceral pain were present in 1 to 3%. At-level neuropathic pain present at 1 month resolved in 45% and below-level pain resolved in 33%. Early (1 month) sensory hypersensitivity (particularly cold-evoked dysesthesia) was a predictor for the development of below-level, but not at-level, SCI pain at 12 months. In conclusion, the present study demonstrates phenotypical differences between at-level and below-level SCI pain, which is important for future studies aiming to uncover underlying pain mechanisms. ⋯ The finding that early sensory hypersensitivity predicts later onset of below-level central neuropathic pain may help to identify patients at risk of developing neuropathic pain conditions after traumatic spinal cord injury. Information about onset of pain may help to identify different phenotypes in neuropathic pain conditions.
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Randomized Controlled Trial
The association between negative affect and prescription opioid misuse in patients with chronic pain: the mediating role of opioid craving.
Over the past decade, considerable research has accumulated showing that chronic pain patients experiencing high levels of negative affect (NA) are at increased risk for prescription opioid misuse. The primary objective of the present study was to examine the factors that underlie the association between NA and prescription opioid misuse among patients with chronic pain. In this study, 82 patients with chronic musculoskeletal pain being prescribed opioid medication completed the Current Opioid Misuse Measure, a well-validated self-report questionnaire designed to assess prescription opioid misuse. Patients were also asked to complete self-report measures of pain intensity, NA, and opioid craving. A bootstrapped multiple mediation analysis was used to examine the mediating role of patients' pain intensity and opioid craving in the association between NA and prescription opioid misuse. Consistent with previous research, we found a significant association between NA and prescription opioid misuse. Interestingly, results revealed that opioid craving, but not pain intensity, mediated the association between NA and opioid misuse. The Discussion addresses the potential psychological and neurobiological factors that might contribute to the interrelationships among NA, opioid craving, and prescription opioid misuse in patients with pain. The clinical implications of our findings are also discussed. ⋯ Our study provides new insights into the factors that underlie the association between negative affect and prescription opioid misuse in patients with chronic pain. Our findings could have important clinical implications, particularly for patients being prescribed opioid medication, and for reducing rates of opioid misuse in patients with pain.
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Review Meta Analysis
Interventions available over the counter and advice for acute low back pain: systematic review and meta-analysis.
This systematic review evaluated evidence from randomized controlled trials investigating interventions available over the counter and advice that could be provided to people with acute low back pain. Searches were conducted on MEDLINE, Embase, Cochrane Database of Systematic Reviews, AMED, CENTRAL, and PsycINFO for eligible randomized controlled trials. The primary outcome measure was pain. Eligible controls included placebo, no treatment, or usual care. Two reviewers extracted data and rated study quality. A random effects model was used to pool trial effects with the overall strength of evidence described using the GRADE criteria. Thirteen randomized controlled trials (2,847 participants) evaluating advice, bed rest, simple analgesics (paracetamol, nonsteroidal anti-inflammatory drugs), heat application, and a topical rubefacient were included. There was low-quality evidence that bed rest is ineffective and very-low-quality evidence that advice is ineffective in the short, intermediate, and long terms. There was very-low-quality evidence that nonsteroidal anti-inflammatory drugs (ibuprofen and diclofenac "when required" dosing) provide an immediate analgesic effect (mean differences -10.9 [95% confidence interval = -17.6 to -4.2] and -11.3 [95% confidence interval = -17.8 to -4.9], respectively). There is very-low-quality evidence that heat wrap and a capsicum-based rubefacient provide an immediate analgesic effect (mean differences -13.5 [95% confidence interval = -21.3 to -5.7] and 17.5, P < .001, respectively), but there was no information on longer-term outcomes. ⋯ There is limited evidence that nonsteroidal anti-inflammatory drugs, heat wrap, and rubefacients provide immediate pain relief for acute back pain and that bed rest and advice are both ineffective. Future research is needed to provide evidence to support rational use of over-the-counter remedies and advice for people with acute low back pain.
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Randomized Controlled Trial Multicenter Study
Determination of the effective dose of pregabalin on human experimental pain using the sequential up-down method.
The intradermal capsaicin pain model has been used to evaluate analgesic effects of a variety of drugs. Using the sequential up-down method, we examined the analgesic effects of pregabalin on intradermal capsaicin pain. Using a double-blind, placebo-controlled, crossover study, healthy adult men were randomized to oral pregabalin or placebo on the first visit and returned for the opposite treatment after a washout period. Dosing was set by the Dixon sequential up-down method; that is, a greater or less than 30% reduction in capsaicin pain decreased or increased the dose, respectively, by a fixed interval for the next subject. The median effective dose (ED50) was derived once 7 changes in dose direction occurred. Secondary outcome measures included secondary hyperalgesia and tactile and thermal allodynia, and their respective areas (cm(2)). Thirteen subjects were required to derive the pregabalin ED50: 252 mg (95% confidence interval 194, 310 mg). Most common side effects were drowsiness (46%), euphoria (31%), and dizziness (7%). Those with ≥30% pain reduction as compared to placebo also had similar reductions in secondary outcome measures. The intradermal capsaicin pain model can be used to efficiently derive the pregabalin ED50, but well-powered dose-response curve studies are needed for comparison and validation. ⋯ Using the Dixon sequential up-down method, the ED50 of pregabalin on intradermal capsaicin induced pain was successfully calculated (252 mg) using only 13 subjects.
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Multicenter Study Comparative Study
Comparisons of patient and physician assessment of pain-related domains in cancer pain classification: results from a large international multicenter study.
The aim of the present study is to compare physician clinical assessment with patient-rated evaluations in the classification of cancer pain patients into groups with different pain levels, according to the presence of incident/breakthrough pain, neuropathic pain, and psychological distress. Average pain in the previous 24 hours was used as the dependent variable in multivariate linear regression models, and incident/breakthrough pain, neuropathic pain, and psychological distress were tested as regressors; in the assessment of regressors, physicians used the Edmonton Classification System for Cancer Pain, whereas patients used structured self-assessment questionnaires. The amount of variability in pain intensity scores explained by the 2 sets of regressors, physician and patient rated, was compared using R(2) values. When tested in 2 separate models, patient ratings explained 20.3% of variability (95% confidence interval [CI] = 15.2-25.3%), whereas physician ratings explained 6.1% (95% CI = 2.2-9.8%). The higher discriminative capability of patient ratings was still maintained when both regressor sets were introduced in the same model, with R(2) indices of 17.6% (95% CI = 13.0-22.2%) for patient ratings vs 3.4% (95% CI = .9-5.9%) for physician ratings. Patients' self-assessment of subjective symptoms should be integrated in future cancer pain classification systems. ⋯ Our results indicate that patient-structured assessment of incident/breakthrough pain, neuropathic pain, and psychological distress significantly contributes to the discrimination of cancer patients with different pain levels. The integration of patient self-assessment tools with more objective clinician assessments can improve the classification of cancer pain.