The journal of pain : official journal of the American Pain Society
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Multicenter Study
Neuropathic aspects of persistent postsurgical pain: a French multicenter survey with a 6-month prospective follow-up.
To investigate the role of peripheral neuropathy in the development of neuropathic postsurgical persistent pain (N-PSPP) after surgery, this French multicentric prospective cohort study recruited 3,112 patients prior to elective cesarean, inguinal herniorrhaphy (open mesh/laparoscopic), breast cancer surgery, cholecystectomy, saphenectomy, sternotomy, thoracotomy, or knee arthroscopy. Besides perioperative data collection, postoperative postal questionnaires built to assess the existence, intensity, and neuropathic features (with the Douleur Neuropathique 4 Questions [DN4]) of pain at the site of surgery were sent at the third and sixth months after surgery. In the 2,397 patients who completed follow-up, the cumulative risk of N-PSPP within the 6 months ranged from 3.2% (laparoscopic herniorrhaphy) to 37.1% (breast cancer surgery). Pain intensity was greater if DN4 was positive and decreased with time since surgery; it depended on the type of surgery. In pain-reporting patients, the response to the DN4 changed from time to time in about 1:4 of the cases. Older age and a low anxiety score were independent protective factors of N-PSPP, whereas a recent negative event, a low preoperative quality of life, and previous history of peripheral neuropathy were risk factors. The type of anesthesia had no influence on the occurrence of N-PSPP.
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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.
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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.