The journal of pain : official journal of the American Pain Society
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National surveys suggest that millions of adults in the United States use complementary health approaches such as acupuncture, chiropractic manipulation, and herbal medicines to manage painful conditions such as arthritis, back pain, and fibromyalgia. Yet, national and per person out-of-pocket (OOP) costs attributable to this condition-specific use are unknown. In the 2007 National Health Interview Survey, the use of complementary health approaches, the reasons for this use, and the associated OOP costs were captured in a nationally representative sample of 5,467 adults. Ordinary least square regression models that controlled for comorbid conditions were used to estimate aggregate and per person OOP costs associated with 14 painful health conditions. Individuals using complementary approaches spent a total of $14.9 billion (standard error [SE] = $.9 billion) on these approaches to manage these painful conditions. Total OOP expenditures by those using complementary approaches for their back pain ($8.7 billion, SE = $.8 billion) far outstripped OOP expenditures for any other condition; the majority of these costs ($4.7 billion, SE = $.4 billion) were for visits to complementary providers. Annual condition-specific per person OOP costs varied from a low of $568 (SE = $144) for regular headaches to a high of $895 (SE = $163) for fibromyalgia. ⋯ Adults in the United States spent $14.9 billion on complementary health approaches (eg, acupuncture, chiropractic manipulation, and herbal medicines) to manage painful conditions including back pain ($8.7 billion). This back pain estimate is almost one-third of the total conventional health care expenditure for back pain ($30.4 billion) and two-thirds higher than conventional OOP expenditures ($5.1 billion).
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Multicenter Study Clinical Trial
The role of psychological factors in persistent pain after caesarean section.
This French multicenter prospective cohort study recruited 391 patients to investigate the risk factors for persistent pain after elective cesarean delivery, focusing on psychosocial aspects adjusted for other known medical factors. Perioperative data were collected and specialized questionnaires were completed to assess reports of pain at the site of surgery. Three dependent outcomes were considered: pain at the third month after surgery (M3, n = 268; risk = 28%), pain at the sixth month after surgery (M6, n = 239; risk = 19%), and the cumulative incidence (up to M6) of neuropathic pain, as assessed using the Douleur Neuropathique 4 questionnaire (n = 218; risk = 24.5%). The neuropathic aspect of reported pain changed over time in more than 60% of cases, pain being more intense if associated with neuropathic features. Whatever the dependent outcome, a high mental component of quality of life (SF-36) was protective. Pain at M3 was also predicted by pain reported during current pregnancy and a history of miscarriage. Pain at M6 was also predicted by report of a postoperative complication. Incident neuropathic pain was predicted by pain reported during current pregnancy, a previous history of a peripheral neuropathic event, and preoperative anxiety.
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Randomized Controlled Trial
Effect of Milnacipran Treatment on Ventricular Lactate in Fibromyalgia : A Randomized, Double-blind, Placebo-controlled Trial.
Milnacipran, a serotonin/norepinephrine reuptake inhibitor, has been approved by the US Food and Drug Administration for the treatment of fibromyalgia (FM). This report presents the results of a randomized, double-blind, placebo-controlled trial of milnacipran conducted to test the hypotheses that a) similar to patients with chronic fatigue syndrome, patients with FM have increased ventricular lactate levels at baseline; b) 8 weeks of treatment with milnacipran will lower ventricular lactate levels compared with baseline levels and with ventricular lactate levels after placebo; and c) treatment with milnacipran will improve attention and executive function in the Attention Network Test compared with placebo. In addition, we examined the results for potential associations between ventricular lactate and pain. Baseline ventricular lactate measured by proton magnetic resonance spectroscopic imaging was found to be higher in patients with FM than in healthy controls (F1,37 = 22.11, P < .0001, partial η(2) = .37). Milnacipran reduced pain in patients with FM relative to placebo but had no effect on cognitive processing. At the end of the study, ventricular lactate levels in the milnacipran-treated group had decreased significantly compared with baseline and after placebo (F1,18 = 8.18, P = .01, partial η(2) = .31). A significantly larger proportion of patients treated with milnacipran showed decreases in both ventricular lactate and pain than those treated with placebo (P = .03). These results suggest that proton magnetic resonance spectroscopic imaging measurements of lactate may serve as a potential biomarker for a therapeutic response in FM and that milnacipran may act, at least in part, by targeting the brain response to glial activation and neuroinflammation. ⋯ Patients treated with milnacipran showed decreases in both pain and ventricular lactate levels compared with those treated with placebo, but, even after treatment, levels of ventricular lactate remained higher than in controls. The hypothesized mechanism for these decreases is via drug-induced reductions of a central inflammatory state.
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Comparative Study
Latent Class Analysis of the Short and Long-Form of the Chronic Pain Acceptance Questionnaire- Further Examination of Patient Subgroups.
A substantial literature indicates that pain acceptance is a useful behavioral process in chronic pain rehabilitation. Pain acceptance consists of willingness to experience pain and to engage in important activities even in the presence of pain and is often measured using the Chronic Pain Acceptance Questionnaire (CPAQ). Previous traditional cluster analyses of the 20-item CPAQ identified 3 patient clusters that differed across measures of patient functioning in meaningful ways. The aims of this study were to replicate the previous study in a new sample, using the more robust method of latent class analysis (LCA), and to compare the cluster structure of the CPAQ and the shorter CPAQ-8. In total, 914 patients with chronic pain completed the CPAQ and a range of measures of psychological and physical function. Patient clusters identified via LCA were then used to compare patients across functional measures. Contrary to previous research, LCA demonstrated that a 4-cluster structure was superior to a 3-cluster structure. Consistent with previous research, cluster membership based on patterns of pain willingness and activity engagement was significantly associated with specific patterns of psychological and physical function, in line with theoretical predictions. These cluster structures were similar for both CPAQ-20 and CPAQ-8 items. These results provide further evidence of the relevance of chronic pain acceptance, and a more nuanced understanding of how the components of acceptance are related to function. ⋯ Pain acceptance is important in chronic pain. The findings of the present study, which included 914 individuals with chronic pain, provide support for 4 discrete groups of patients based on levels of acceptance (low, medium, and high), as well as a group with a high level of activity engagement and low willingness to have pain. These groups appear statistically robust and differed in predictable ways across measures of functioning.
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Generalized dysfunction of the nociceptive system has been hypothesized to be an important pathophysiologic process underlying temporomandibular disorder (TMD) pain. Studies have not identified sensitization to painful stimuli administered prospectively across consecutive days among participants with TMD with chronic pain. We attempted to isolate an empirically derived laboratory-based marker of sustained mechanical pain sensitization. We examined whether this index accounted for variance in prospective assessments of clinical TMD pain. Participants were women with a clinical diagnosis of chronic TMD (n = 30) and healthy female controls (n = 30). Pain thresholds were assessed using digital algometry 4 times at 12-hour intervals over 48 consecutive hours and clinical TMD pain via follow-up telephone assessments. Sustained mechanical pain sensitization, defined by statistically significant linear decrements in pressure pain thresholds across the consecutive testing sessions, discriminated chronic TMD and control participants. An index of sustained sensitization at the masseter accounted for unique variance in clinical TMD pain over the subsequent 3-month assessment period, even controlling for mean pain threshold and baseline pain severity. These preliminary findings highlight discriminant and predictive validity characteristics of a novel marker of protracted pain sensitization among women with chronic TMD pain. ⋯ A laboratory-based and empirically defined marker of sustained mechanical pain sensitization over the course of days with acceptable discriminant and predictive validity was identified. This marker may represent a clinically useful marker of chronic TMD pain in women.