The journal of pain : official journal of the American Pain Society
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Review Meta Analysis
Placebo responses in long-standing complex regional pain syndrome: a systematic review and meta-analysis.
The typical placebo response (ie, the nonspecific effects in the placebo group including benign natural course, regression to the mean, expectation/conditioning effects, and others) in randomized trials in complex regional pain syndrome (CRPS) is unknown. We recently observed a surprising near-absence of placebo response in a randomized controlled trial we conducted on patients with long-standing (≥6 months) CRPS. To investigate the idea that there may be an absence of placebo response in long-standing CRPS further, we conducted a systematic review and meta-analysis of placebo responses in randomized controlled trials conducted in patients with CRPS of ≥6 months. We systematically identified suitable randomized controlled trials published between 1966 and September 2013. We calculated the mean difference and standard error of the mean difference for placebo responses and synthesized individual effect sizes at 4 specified time periods of interest (15-30 minutes, 1 week, 3-4 weeks, and 6 weeks or more) via meta-analysis using the method of inverse-variance. Heterogeneity was assessed according to the I(2) statistic. For primary analysis, we pooled trial-specific effect sizes over the 4 time points. We analyzed data from 340 participants from 18 trials out of a possible 361 participants from 20 trials (94% of participants analyzed). Significant heterogeneity was present between trials; therefore, we interpreted trends from visual inspection of individual trials and pooled estimates. Placebo response was significant at the earliest time period (15-30 minutes). There was no significant evidence of placebo response at any of the other time periods. These results inform the design of future trials, and they caution against the "therapeutic" use of placebo in long-standing CRPS. ⋯ In this meta-analysis of placebo responses in randomized controlled trials in long-standing CRPS, published during 1966 to 2013, we found no evidence for placebo analgesia, except at very early time points. Results inform the design of future placebo analgesia research in long-standing CRPS.
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Review Meta Analysis
Is tactile acuity altered in people with chronic pain? a systematic review and meta-analysis.
Impaired tactile acuity in people with chronic pain conditions has been suggested to reflect altered cortical representation of the painful body part, and treatments that aim to improve tactile acuity in these conditions have shown clinical benefit. Whether abnormalities in tactile acuity are a consistent feature of chronic pain remains largely unknown. The aim of this review was to systematically evaluate the literature and use meta-analysis to establish whether tactile acuity is altered in people with chronic non-neuropathic pain. We systematically searched the literature for studies that investigated tactile acuity in people with chronic non-neuropathic pain and compared it to an appropriate control group. Sixteen studies, reporting data from 5 chronic pain conditions, were included. Data were available for 18 chronic pain populations (n = 484) and 15 control populations (n = 378). Our results suggest that tactile acuity is diminished in arthritis, complex regional pain syndrome, and chronic low back pain but not in burning mouth syndrome. The strength of the available evidence is weakened by somewhat inconsistent results and the high risk of bias observed in all of the included studies. ⋯ This systematic review synthesizes the evidence for tactile acuity deficits in people with chronic non-neuropathic pain. The findings suggest that tactile acuity deficits may be characteristic of chronic pain. That tactile acuity training may benefit those with chronic pain disorders suggests that clinical trials may be warranted.
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Review Meta Analysis
Incidence and severity of chronic pain at 3 and 6 months after thoracotomy: meta-analysis.
This systematic review was performed to determine the incidence and the severity of chronic pain at 3 and 6 months after thoracotomy based on meta-analyses. We conducted MEDLINE, Web of Science, and Google Scholar searches of databases and references for English articles; 858 articles were reviewed. Meta-regression analysis based on the publication year was used to examine if the chronic pain rates changed over time. Event rates and confidence intervals with random effect models and Freeman-Tukey double arcsine variance-stabilizing transformation were obtained separately for the incidence of chronic pain based on 1,439 patients from 17 studies at 3 months and 1,354 patients from 15 studies at 6 months. The incidences of chronic pain at 3 and 6 months after thoracotomy were 57% (95% confidence interval [CI], 51-64%) and 47% (95% CI, 39-56%), respectively. The average severity of pain ratings on a 0 to 100 scale at these times were 30 ± 2 (95% CI, 26-35) and 32 ± 7 (95% CI, 17-46), respectively. Reported chronic pain rates have been largely stable at both 3 and 6 months from the 1990s to the present. ⋯ This systematic review's findings suggest that reported chronic pain rates are approximately 50% at 3 and 6 months and have been largely stable from the 1990s to the present. The severity of this pain is not consistently reported. Chronic pain after thoracotomy continues to be a significant problem despite advancing perioperative care.
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Review Meta Analysis
Self-efficacy and chronic pain outcomes: a meta-analytic review.
A meta-analysis was performed to evaluate overall strengths of relation between self-efficacy (SE) and functioning (pain severity, functional impairment, affective distress) in chronic pain samples, as well as potential moderating effects of sociodemographic characteristics and methodologic factors on these associations. In sum, 86 samples (N = 15,616) fulfilled selection criteria for analysis. SE had negative overall correlations with impairment, affective distress, and pain severity although considerable heterogeneity was observed for all effect sizes. Age, pain duration, SE scale content (SE for functioning despite pain vs SE for pain control vs SE for managing other symptoms such as emotional distress) and type of impairment measure (self-report vs task performance) had significant moderating effects on SE-impairment associations. SE-affective distress relations were moderated by employment status and SE scale content. Finally, moderator analyses of studies having longitudinal designs indicated associations between baseline SE, and each outcome at follow-up remained significant in prospective studies that had statistically controlled for effects of baseline responses on that outcome. Hence, SE is a robust correlate of key outcomes related to chronic pain and a potentially important risk/protective factor that has implications for subsequent functioning in affected groups. ⋯ Meta-analysis indicated that SE has significant overall associations with impairment, affective distress, and pain severity within chronic pain samples and identified several factors that contribute to variability in effect sizes. Findings highlighted SE as a robust correlate and potentially important risk/protective factor for subsequent adjustment in affected groups.
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Review Meta Analysis
Local infiltration analgesia for postoperative pain after hip arthroplasty: a systematic review and meta-analysis.
Postoperative pain after hip arthroplasty (HA) is very common and severe. Currently, use of routine analgesic methods is often accompanied by adverse events (AEs). Local infiltration analgesia (LIA) for controlling pain has been a therapeutic option in many surgical procedures. However, its analgesic efficacy in HA and its safety remain unclear. Data from 9 randomized controlled trials, involving 760 participants, comparing the effect of LIA with that of placebo infiltration or no infiltration on patients undergoing HA were retrieved from an electronic database, and the pain scores, analgesic consumption, and AEs were analyzed. Effects were summarized using weighted mean differences, standardized mean differences, or odds ratio with fixed or random effect models. There was strong evidence of an association between LIA and reduced pain scores at 4 hours at rest (P < .00001) and with motion (P < .00001), 6 hours with motion (P = .02), and 24 hours at rest (P = .01), and decreased analgesic consumption during 0 to 24 hours (P = .001) after HA. These analgesic efficacies for LIA were not accompanied by any increased risk for AEs. However, the current meta-analysis did not reveal any associations between LIA and the reduced pain scores or analgesic consumption at other time points. The results suggest that LIA can be used for controlling pain after HA because of its efficacy in reducing pain scores and thus can reduce analgesic consumption on the first day without increased risk of AEs. ⋯ This is the first pooled database meta-analysis to assess the analgesic effects and safety of LIA in controlling pain after HA. The derived information offers direct evidence that LIA can be used for patients undergoing HA because of its ability to reduce pain scores and analgesic consumption without any additional AEs.