Pain
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Randomized Controlled Trial Comparative Study
Predicting outcome of TENS in chronic pain: a prospective, randomized, placebo controlled trial.
Transcutaneous electrical nerve stimulation (TENS) is an easy to use non-invasive analgesic intervention applied for diverse pain states. However, effects in man are still inconclusive, especially for chronic pain. Therefore, to explore the factors predicting result of TENS treatment in chronic pain we conducted a prospective, randomized, placebo-controlled trial (n=163), comparing high frequency TENS (n=81) with sham TENS (n=82). Patients' satisfaction (willingness to continue treatment; yes or no) and pain intensity (VAS) were used as outcome measures. The origin of pain and cognitive coping strategies were evaluated as possible predictors for result of TENS treatment. ⋯ Fifty-eight percent of the patients in the TENS group and 42.7% of the sham-TENS group were satisfied with treatment result (chi square=3.8, p=0.05). No differences were found for pain intensity. Patients diagnosed with osteoarthritis and related disorders (especially of the vertebral column) or peripheral neuropathic pain were less satisfied with high frequency TENS (OR=0.12 (95% CI 0.04-0.43) and 0.06 (95% CI 0.006-0.67), respectively). Injury of bone and soft tissue (especially postsurgical pain disorder) provided the best results. Treatment modality or interactions with treatment modality did not predict intensity of pain as a result of treatment. We conclude, that predicting the effect of high frequency TENS in chronic pain depends on the choice of outcome measure. Predicting patients' satisfaction with treatment result is related to the origin of pain. Predicting pain intensity reflects mechanisms of pain behavior and perceived control of pain, independent of treatment modality. Pain catastrophizing did not predict TENS treatment outcome.
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In many countries timely access to care is a growing problem. As medical costs escalate health care resources must be prioritized. In this context there is an increasing need for benchmarks and best practices in wait-time management. ⋯ It was concluded that wait-times for chronic pain treatment of 6 months or longer are medically unacceptable. Further study is necessary to determine at what stage the deterioration begins from the onset of pain to treatment and the impact of waiting on treatment outcomes. Most important is the need to improve access to appropriate care for patients with chronic pain, an escalating public health care problem with significant human and economic costs.
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Randomized Controlled Trial Comparative Study
Pregabalin in patients with central neuropathic pain: a randomized, double-blind, placebo-controlled trial of a flexible-dose regimen.
The effective treatment of patients suffering from central neuropathic pain remains a clinical challenge, despite a standard pharmacological approach in combination with anticonvulsants and antidepressants. A randomized, double-blinded, placebo-controlled trial evaluated the effects of pregabalin on pain relief, tolerability, health status, and quality of life in patients with central neuropathic pain caused by brain or spinal cord injuries. At baseline and 4 weeks after the start of treatment subjects were evaluated with standard measures of efficacy: pain intensity measured by visual analog scale, health status (Pain Disability Index and EQ-5D) and quality of life (SF-36). ⋯ Pregabalin treatment led to a significant improvement in the bodily pain domain of the SF36. In the other domains, more favorable scores were reported without reaching statistical significance. Pregabalin, in a flexible-dose regime, produced clinically significant reductions in pain, as well as improvements in health status in patients suffering from severe central neuropathic pain.
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Comparative Study
Individual differences in pain sensitivity: genetic and environmental contributions.
Large individual differences in pain sensitivity present a challenge for medical diagnosis and may be of importance for the development of chronic pain. Variance in pain sensitivity is partially mediated by genetic factors, but the extent of this contribution is uncertain. We examined cold-pressor pain and contact heat pain in 53 identical (MZ) and 39 fraternal (DZ) twin pairs, and 4 single twins to determine the heritability of the two phenotypes, and the extent to which the same genetic and environmental factors affect both pain modalities. ⋯ These findings demonstrate that cold-pressor pain and contact heat pain are mainly distinct phenomena from both a genetic and an environmental standpoint. This may partly explain disparate results in genetic association studies and argues for caution in generalizing genetic findings from one pain modality to another. It also indicates that differences in pain scale usage account for a minor portion of the variance, providing strong support for the validity of subjective pain ratings as measures of experienced pain.
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Comparative Study
Evidence for a biopsychosocial influence on shoulder pain: pain catastrophizing and catechol-O-methyltransferase (COMT) diplotype predict clinical pain ratings.
The experience of pain is believed to be influenced by social, cultural, environmental, psychological, and genetic factors. Despite this assertion, few studies have included clinically relevant pain phenotypes when investigating interactions among these variables. This study investigated whether psychological variables specific to fear-avoidance models and catechol-O-methyltransferase (COMT) genotype influenced pain ratings for a cohort of patients receiving operative treatment of shoulder pain. ⋯ A hierarchical regression model indicated that an interaction between pain catastrophizing and COMT diplotype contributed additional variance in pre-operative pain ratings. The pain catastrophizingxCOMT diplotype interaction demonstrated predictive validity as patients with high pain catastrophizing and low COMT activity (APS/HPS group) were more likely (RR=6.8, 95% CI=2.8-16.7) to have post-operative pain ratings of 4.0/10 or higher. Our findings suggest that an interaction between pain catastrophizing and COMT diplotype has the potential to influence pain ratings in patients seeking operative treatment of their shoulder pain.