The journal of pain : official journal of the American Pain Society
-
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.
-
Complex regional pain syndrome (CRPS) is a distressing and difficult-to-treat complication of wrist fracture. Estimates of the incidence of CRPS after wrist fracture vary greatly. It is not currently possible to identify who will go on to develop CRPS after wrist fracture. In this prospective cohort study, a nearly consecutive sample of 1,549 patients presenting with wrist fracture to 1 of 3 hospital-based fracture clinics and managed nonsurgically was assessed within 1 week of fracture and followed up 4 months later. Established criteria were used to diagnose CRPS. The incidence of CRPS in the 4 months after wrist fracture was 3.8% (95% confidence interval = 2.9-4.8%). A prediction model based on 4 clinical assessments (pain, reaction time, dysynchiria, and swelling) discriminated well between patients who would and would not subsequently develop CRPS (c index .99). A simple assessment of pain intensity (0-10 numerical rating scale) provided nearly the same level of discrimination (c index .98). One in 26 patients develops CRPS within 4 months of nonsurgically managed wrist fracture. A pain score of ≥5 in the first week after fracture should be considered a "red flag" for CRPS. ⋯ This study shows that excessive baseline pain in the week after wrist fracture greatly elevates the risk of developing CRPS. Clinicians can consider a rating of greater than 5/10 to the question "What is your average pain over the last 2 days?" to be a "red flag" for CRPS.
-
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.
-
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.
-
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.