Pain
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Comparative Study
Illness perceptions of low back pain patients in primary care: what are they, do they change and are they associated with outcome?
We describe the illness perceptions of patients with low back pain, how they change over 6 months, and their associations with clinical outcome. Consecutive patients consulting eight general practices were eligible to take part in a prospective cohort study, providing data within 3 weeks of consultation and 6 months later. Illness perceptions were measured using the Revised Illness Perception Questionnaire (IPQ-R). ⋯ There were strong, statistically significant, associations (RRs of 1.4 and over) between IPQ-R baseline consequences, timeline acute/chronic, personal control and treatment control scores and poor outcome. Patients who expected their back problem to last a long time, who perceived serious consequences, and who held weak beliefs in the controllability of their back problem were more likely to have poor clinical outcomes 6 months after they consulted their doctor. These results have implications for the management of patients, and support the need to assess and address patients' cognitions about their back problems.
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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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Editorial Comment
Placebo analgesia and nocebo hyperalgesia--two sides of the same coin?
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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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The nocebo effect consists in delivering verbal suggestions of negative outcomes so that the subject expects clinical worsening. Here we show that nocebo suggestions, in which expectation of pain increase is induced, are capable of producing both hyperalgesic and allodynic responses. By extending previous findings on the placebo effect, we investigated the role of learning in the nocebo effect by means of a conditioning procedure. ⋯ Therefore, in contrast to placebo analgesia, whereby a conditioning procedure elicits larger effects compared to verbal suggestions alone, learning seems to be less important in nocebo hyperalgesia. Overall, these findings indicate that, by defining hyperalgesia as an increase in pain sensitivity and allodynia as the perception of pain in response to innocuous stimulation, nocebos can indeed produce both hyperalgesic and allodynic effects. These results also suggest that learning is not important in nocebo hyperalgesia compared to placebo analgesia.