The journal of pain : official journal of the American Pain Society
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Review Meta Analysis
Conditioned pain modulation in populations with chronic pain: a systematic review and meta-analysis.
A systematic literature review and meta-analysis were undertaken to determine if conditioned pain modulation is dysfunctional in populations with chronic pain. Studies that used a standardized protocol to evaluate conditioned pain modulation in a chronic pain population and in a healthy control population were selected and reviewed. Thirty studies were included in the final review, encompassing data from 778 patients and 664 control participants. Across all studies there was a large effect size of .78, reflecting reduced conditioned pain modulation in the patient group. Analysis of moderator variables indicated a significant influence of participant gender and age on the effect size. Methodological moderator variables of type of outcome measure, type of test stimulus, type of conditioning stimulus, and the level of conditioning stimulus pain were not significant. A risk of bias assessment indicated that poor blinding of assessors and a lack of control of confounding variables were common. It is concluded that conditioned pain modulation is impaired in populations with chronic pain. Future studies should ensure adequate matching of participant age and gender between patient and control groups, blinding of the assessors obtaining the outcome measures, and more rigorous control for variables known to influence the level of modulation. ⋯ This review compared the efficacy of conditioned pain modulation between chronic pain and healthy populations. The finding of impaired modulation in the chronic pain groups highlights the dysfunction of endogenous pain modulatory mechanisms in this population.
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Review Meta Analysis
Effects of yoga interventions on pain and pain-associated disability: a meta-analysis.
We searched databases for controlled clinical studies, and performed a meta-analysis on the effectiveness of yoga interventions on pain and associated disability. Five randomized studies reported single-blinding and had a higher methodological quality; 7 studies were randomized but not blinded and had moderate quality; and 4 nonrandomized studies had low quality. In 6 studies, yoga was used to treat patients with back pain; in 2 studies to treat rheumatoid arthritis; in 2 studies to treat patients with headache/migraine; and 6 studies enrolled individuals for other indications. All studies reported positive effects in favor of the yoga interventions. With respect to pain, a random effect meta-analysis estimated the overall treatment effect at SMD = -.74 (CI: -.97; -.52, P < .0001), and an overall treatment effect at SMD = -.79 (CI: -1.02; -.56, P < .0001) for pain-related disability. Despite some limitations, there is evidence that yoga may be useful for several pain-associated disorders. Moreover, there are hints that even short-term interventions might be effective. Nevertheless, large-scale further studies have to identify which patients may benefit from the respective interventions. ⋯ This meta-analysis suggests that yoga is a useful supplementary approach with moderate effect sizes on pain and associated disability.
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Review Meta Analysis Comparative Study
Comparative efficacy and harms of duloxetine, milnacipran, and pregabalin in fibromyalgia syndrome.
Duloxetine (DLX), milnacipran (MLN), and pregabalin (PGB) are the only drugs licensed by the US Food and Drug Administration (FDA) for fibromyalgia syndrome (FMS). Evidence on the comparative benefits and harms is still accruing. The authors searched MEDLINE, SCOPUS, Cochrane Central Register of Controlled Trials, and sought unpublished data from the databases of FDA, US National Institutes for Health, and Industry through May 2009 for randomized controlled trials. Outcomes of interest were symptom reduction (pain, fatigue, sleep disturbance, depressed mood, reduced health-related quality of life), and adverse events. 17 studies with 7,739 patients met the inclusion criteria. The 3 drugs were superior to placebo except DLX for fatigue, MLN for sleep disturbance, and PGB for depressed mood. Adjusted indirect comparisons indicated no significant differences for 30% pain relief and dropout rates due to adverse events between the 3 drugs. Significant differences in average symptom reduction were found: DLX and PGB were superior to MLN in reduction of pain and sleep disturbances. DLX was superior to MLN and PGB in reducing depressed mood. MLN and PGB were superior to DLX in reducing fatigue. The risk of headache and nausea with DLX and MLN was higher compared with PGB. The risk of diarrhea was higher with DLX compared to MLN and PGB. There is evidence for the short-term (up to 6 months) efficacy of DLX, MLN, and PGB. Differences with regard to the occurrence of the key symptoms of FMS and to drug-specific adverse events may be relevant for the choice of medication. ⋯ This article presents comparative data on the efficacy and harms of duloxetine, milnacipran, and pregabalin in fibromyalgia syndrome. The results can help clinicians in choosing medication since the 3 drugs have different effects on the key symptoms of fibromyalgia syndrome and differences in side effects, contraindications, and warnings.
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This pooled individual data (PID)-based meta-analysis collectively assessed the analgesic effect of repetitive transcranial magnetic stimulation (rTMS) on various neuropathic pain states based on their neuroanatomical hierarchy. Available randomized controlled trials (RCTs) were screened. PID was coded for age, gender, pain neuroanatomical origins, pain duration, and treatment parameters analyses. Coded pain neuroanatomical origins consist of peripheral nerve (PN); nerve root (NR); spinal cord (SC); trigeminal nerve or ganglion (TGN); and post-stroke supraspinal related pain (PSP). Raw data of 149 patients were extracted from 5 (1 parallel, 4 cross-over) selected (from 235 articles) RCTs. A significant (P < .001) overall analgesic effect (mean percent difference in pain visual analog scale (VAS) score reduction with 95% confidence interval) was detected with greater reduction in VAS with rTMS in comparison to sham. Including the parallel study (Khedr et al), the TGN subgroup was found to have the greatest analgesic effect (28.8%), followed by PSP (16.7%), SC (14.7%), NR (10.0%), and PN (1.5%). The results were similar when we excluded the parallel study with the greatest analgesic effect observed in TGN (33.0%), followed by SC (14.7%), PSP (10.5%), NR (10.0%), and PN (1.5%). In addition, multiple (vs single, P = .003) sessions and lower (>1 and < or =10 Hz) treatment frequency range (vs >10 Hz) appears to generate better analgesic outcome. In short, rTMS appears to be more effective in suppressing centrally than peripherally originated neuropathic pain states. ⋯ This is the first PID-based meta-analysis to assess the differential analgesic effect of rTMS on neuropathic pain based on the neuroanatomical origins of the pain pathophysiology and treatment parameters. The derived information serves as a useful resource in regards to treatment parameters and patient population selection for future rTMS-pain studies.
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Meta Analysis
Acupuncture for tension-type headache: a meta-analysis of randomized, controlled trials.
We investigated the efficacy and safety of acupuncture for the treatment of tension-type headache by conducting a systematic review and meta-analysis of randomized, controlled trials. The Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, CINAHL, and PsycINFO were searched from inception through August 2007. No search or language restrictions were applied. Eight randomized, controlled trials met our inclusion criteria. Pooled data from 5 studies were used for the meta-analysis. Our primary outcome was headache days per month. We assessed data from 2 time points: During treatment and at long-term follow-up (20-25 weeks). The weighted mean difference (WMD) between acupuncture and sham groups was used to determine effect size, and a validated scale was used to assess the methodological quality of included studies. During treatment, the acupuncture group averaged 8.95 headache days per month compared with 10.5 in the sham group (WMD, -2.93 [95% CI, -7.49 to 1.64]; 5 trials). At long-term follow-up, the acupuncture group reported an average of 8.21 headache days per month compared with 9.54 in the sham group (WMD, -1.83[95% CI, -3.01 to -0.64]; 4 trials). The most common adverse events reported were bruising, headache exacerbation, and dizziness. ⋯ This meta-analysis suggests that acupuncture compared with sham for tension-type headache has limited efficacy for the reduction of headache frequency. There exists a lack of standardization of acupuncture point selection and treatment course among randomized, controlled trials. More research is needed to investigate the treatment of specific tension-type headache subtypes.