The journal of pain : official journal of the American Pain Society
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Fibromyalgia (FM) is a chronic, widespread musculoskeletal pain disorder that is very prevalent in the general population (approximately 5%). Accumulating evidence suggests that FM is associated with central pain processing abnormalities, ie, central sensitization. Several previous studies of chronic pain patients, including FM, have shown gray matter atrophy of brain areas associated with sensory and affective pain processing. These findings, however, have not been confirmed in all FM studies. In this study, we investigated gray matter volumes of brain areas associated with pain-related areas of FM patients identified by functional brain imaging. Using voxel-based morphometric (VBM) analysis of magnetic resonance brain images, we compared 19 pain-related brain areas of 14 female FM patients and 11 healthy controls (NC). We found that FM patients had significantly less gray matter volumes than NC in 3 of these brain regions, including the anterior and mid-cingulate, as well as mid-insular cortices. Importantly, FM patients demonstrated neither global gray matter atrophy nor gray matter changes associated with depression, as shown in some studies. Using a more stringent analysis than other VBM studies, we provide evidence for decreased gray matter volumes in a number of pain-related brain areas in FM. Although the mechanisms for these gray matter changes are presently unclear, they may contribute to some of the core features of this chronic disorder including affective disturbances and chronic widespread pain. ⋯ Increasing evidence supports the association of chronic pain with accelerated gray matter atrophy in pain disorders like low back pain, IBS, and FM syndrome. However, cause-effect relationships between chronic pain and decreased gray matter volumes have not been established yet and will require future prospective studies.
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The Tampa Scale for Kinesiophobia (TSK) is one of the most frequently employed measures for assessing pain-related fear in pain patients. Although the TSK has been translated into different languages, a Spanish version of the TSK has not been available, up to now. Thus, the aim of this study was to validate the Spanish version of the TSK in 2 different pain samples: A heterogeneous chronic pain sample (n = 125) and a musculoskeletal acute pain sample (n = 86). Factor analysis revealed a 2-factor model of 11 items replicated on both samples, named TSK-11. The instrument obtained shows good reliability (internal consistency and stability) and validity (convergent and predictive), with the advantage of brevity. Evidence is provided on discriminant validity between both TSK factors (called Activity Avoidance and Harm). The Harm factor shows the best predictive validity, as it predicts pain persistence, catastrophizing, depression, and pain intensity scores after 6 months. Changes in the Activity Avoidance factor are positively correlated with changes in catastrophizing and anxiety, and negatively associated with changes in functional status. The results of this study point to the relative contribution of both components of pain-related fear to pain adjustment. ⋯ This article presents the Spanish version of the TSK. Factor analysis revealed a 2-factor model (called Activity Avoidance and Harm). The version obtained shows good reliability and validity. Results provide clinicians with access to a measure of pain-related fear for Spanish-speaking pain patients, offering the advantage of brevity.
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Review Comparative Study
Systematic review of the comparative effectiveness of antiepileptic drugs for fibromyalgia.
Fibromyalgia is a difficult-to-treat chronic pain syndrome that affects 2% of the US population. Pregabalin is an antiepileptic recently FDA approved for fibromyalgia treatment. Other antiepileptics have been suggested for treatment. This systematic review examines the relative benefits and harms of antiepileptic drugs in the treatment of fibromyalgia. A literature search was conducted and 8 studies matched criteria (7 studies of pregabalin, 1 of gabapentin). Both drugs reduced mean pain scores more than placebo at a modest rate (pregabalin, 38% to 50%; gabapentin, 51%). In a 6-month trial of pregabalin responders, 32% continued to have response at 6 months, with a mean time to loss of response of 34 days. Compared to placebo, the drugs had similarly high rates of adverse events and withdrawals. Without a head-to-head trial it is not possible to conclude if 1 antiepileptic is more effective or harmful than the other, although limited evidence suggests potential differences. Future studies must directly compare the drugs, include a more broadly defined population, examine long term benefits and harms, and include cointerventions. We conclude that pregabalin and gabapentin are modestly effective for the treatment of fibromyalgia but that their long-term safety and efficacy remain unknown. ⋯ This systematic review evaluates the benefits and harms of using the antiepileptic drugs gabapentin and pregabalin for the treatment of fibromyalgia. Conclusions from this paper can help clinicians to more effectively treat the pain associated with fibromyalgia.
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Global ratings of treatment satisfaction and improvement can provide an opportunity for patients to aggregate multiple aspects of their treatment into a single measure of its perceived benefits and disadvantages. Although such measures have been recommended for chronic pain clinical trials, only limited data are available that address the hypothesis that they reflect multiple aspects of patients' treatment experience. Our objective was to identify the factors that make independent contributions to ratings of treatment satisfaction. We analyzed data from 5 open-label clinical trials of lidocaine patch 5% in osteoarthritis knee pain and chronic low back pain that were 2 to 12 weeks in duration. A total of 383 patients completed the Patient Global Assessment of Treatment Satisfaction scale and measures of pain, interference with physical and emotional functioning, sleep interference, and adverse events. The results of multivariate analyses indicated that improvements in measures of pain intensity, pain relief, and interference with physical functioning each made independent contributions to treatment satisfaction in both groups of patients. Improvements in interference with emotional functioning and sleep and the presence and severity of adverse events were not associated with satisfaction. ⋯ Measures of treatment satisfaction can reflect different aspects of the patient's treatment response, including improvements in pain and physical functioning. Increased understanding of such global measures may facilitate development of clinical trial outcomes that allow patients to evaluate with minimal burden those aspects of the treatment experience they consider personally meaningful.
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A large proportion of oncology outpatients with bone metastasis report unrelieved pain that significantly interferes with daily functioning and quality of life. However, little is known about the longitudinal pattern of pain intensity and analgesic prescriptions or use. Moreover, despite considerable advantages, the use of sophisticated statistical techniques, such as hierarchical linear modeling (HLM) has not been applied to the study of pain and analgesic outcomes. In a prospective longitudinal study, HLM was used to explore predictors of pain intensity and analgesic prescription and intake at the time of enrollment into the study (intercept) and over the course of 6 weeks (trajectory) in a sample of oncology outpatients with bone metastasis who received standard care for pain. In addition to corroborating known predictors of pain intensity, previously unrecognized variables were found that appear to affect both pain and analgesic outcomes. Importantly, some of the predictors of the trajectories of pain intensity and analgesic use (ie, pain-related distress and Pain Management Index (PMI) scores) are particularly amenable to interventions. Findings from this study suggest that sophisticated statistical modeling can be used in pain research to identify individual risk factors and propose novel targets that can be used to improve pain management in oncology outpatients with bone metastasis. ⋯ Findings from this study suggest that a large amount of inter-individual variability exists in patients' experiences with cancer pain and analgesic use. Future studies need to elucidate the mechanisms that underlie these differences.