The journal of pain : official journal of the American Pain Society
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Neuropathic pain is a debilitating condition caused by a lesion or disease of the somatosensory nervous system. Statins inhibit the rate-limiting step in cholesterol biosynthesis by blocking 3-hydroxy-3-methyl glutaryl coenzyme A reductase. Apart from the cholesterol-reducing actions of statins, recent studies have shown their pleiotropic actions; accordingly, their usefulness in attenuating different disease states has been described in preclinical studies. Studies in animals have also suggested their beneficial effects in attenuating neuropathic pain in various animal models of neuropathy. In these studies, their usefulness has been ascribed to cholesterol-independent actions, including anti-inflammatory, antioxidant, and neuromodulatory effects. On the contrary, clinical evidence suggests that statin administration in patients is associated with development of neuropathy, suggesting the dichotomous role of statins in neuropathic pain. The present review discusses the pain-attenuating as well as pain-inducing role of statins in preclinical and clinical studies, respectively. Furthermore, the review provides mechanistic insight to explain the paradoxical nature of this class of drugs in neuropathy in preclinical and clinical studies. ⋯ The article reviews the pain-inducing role of statins in clinical studies and its neuropathic pain-attenuating role in preclinical studies with possible mechanisms. Understanding key differences in mechanisms may help to attenuate pain induction in the clinical setting and may possibly project statins as neuropathic pain-attenuating agents.
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Whether patients receive guideline-concordant opioid therapy (OT) is largely unknown and may vary based on provider and patient characteristics. We assessed the extent to which human immunodeficiency virus (HIV)-infected and uninfected patients initiating long-term (≥ 90 days) OT received care concordant with American Pain Society/American Academy of Pain Medicine and Department of Veterans Affairs/Department of Defense guidelines by measuring receipt of 17 indicators during the first 6 months of OT. Of 20,753 patients, HIV-infected patients (n = 6,604) were more likely than uninfected patients to receive a primary care provider visit within 1 month (52.0% vs 30.9%) and 6 months (90.7% vs 73.7%) and urine drug tests within 1 month (14.8% vs 11.5%) and 6 months (19.5% vs 15.4%; all P < .001). HIV-infected patients were also more likely to receive OT concurrent with sedatives (24.6% vs 19.6%) and a current substance use disorder (21.6% vs 17.2%). Among both patient groups, only modest changes in guideline concordance were observed over time: urine drug tests and OT concurrent with current substance use disorders increased, whereas sedative coprescriptions decreased (all Ps for trend < .001). Over a 10-year period, on average, patients received no more than 40% of recommended care. OT guideline-concordant care is rare in primary care, varies by patient/provider characteristics, and has undergone few changes over time. ⋯ The promulgation of OT clinical guidelines has not resulted in substantive changes over time in OT management, which falls well short of the standard recommended by leading medical societies. Strategies are needed to increase the provision of OT guideline-concordant care for all patients.
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There is emerging evidence that chronic musculoskeletal pain is associated with anatomic and functional abnormalities in gray matter. However, little research has investigated the relationship between chronic musculoskeletal pain and white matter. In this study, we used whole-brain tract-based spatial statistics and region-of-interest analyses of diffusion tensor imaging data to demonstrate that patients with chronic musculoskeletal pain exhibit several abnormal metrics of white matter integrity compared with healthy controls. Chronic musculoskeletal pain was associated with lower fractional anisotropy in the splenium of the corpus callosum and the left cingulum adjacent to the hippocampus. Patients also had higher radial diffusivity in the splenium, right anterior and posterior limbs of the internal capsule, external capsule, superior longitudinal fasciculus, and cerebral peduncle. Patterns of axial diffusivity (AD) varied: patients exhibited lower AD in the left cingulum adjacent to the hippocampus and higher AD in the anterior limbs of the internal capsule and in the right cerebral peduncle. Several correlations between diffusion metrics and clinical variables were also significant at a P < .01 level: fractional anisotropy in the left uncinate fasciculus correlated positively with total pain experience and typical levels of pain severity. AD in the left anterior limb of the internal capsule and left uncinate fasciculus was correlated with total pain experience and typical pain level. Positive correlations were also found between AD in the right uncinate and both total pain experience and pain catastrophizing. These results demonstrate that white matter abnormalities play a role in chronic musculoskeletal pain as a cause, a predisposing factor, a consequence, or a compensatory adaptation. ⋯ Patients with chronic musculoskeletal pain exhibit altered metrics of diffusion in the brain's white matter compared with healthy volunteers, and some of these differences are directly related to symptom severity.
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There has been a need for a brief assessment tool to determine compliance with use of prescribed opioids for pain. The purpose of this study was to develop and begin the validation of a brief and simple compliance checklist (Opioid Compliance Checklist [OCC]) for chronic pain patients prescribed long-term opioid therapy. A review of the literature of opioid therapy agreements led to a 12-item OCC that was repeatedly administered to 157 patients who were taking opioids for chronic pain and followed for 6 months. Validation of the OCC was conducted by identifying those patients exhibiting aberrant drug-related behavior as determined by any of the following: positive urine toxicology screen, a positive score on the Prescription Drug Use Questionnaire interview or Current Opioid Misuse Measure, and/or ratings by staff on the Addiction Behavior Checklist. Of the original 12 items, 5 OCC items appeared to best predict subsequent aberrant behaviors based on multivariate logistic regression analyses (cross-validated area under the receiver operating characteristic curve = .67). Although further testing is needed, these results suggest that the OCC is an easy-to-use, promising measure in monitoring opioid adherence among persons with chronic pain. ⋯ This study presents validation of a brief 5-item compliance checklist for use with chronic pain patients prescribed long-term opioid therapy. This measure asks patients about aberrant drug-related behavior over the past month, and any positive response indicates problems with adherence with opioids. Further cross-validation testing is needed.
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Current fear-avoidance models consider pain-related fear as a crucial factor in the development of chronic pain. However, pain-related fear often occurs in a context of multiple, competing goals. This study investigated whether pain-related fear and avoidance behavior are attenuated when individuals are faced with a pain avoidance goal and another valued but competing goal, operationalized as obtaining a monetary reward. Fifty-five healthy participants moved a joystick toward different targets. In the experimental condition, a movement to one target (conditioned stimulus [CS+]) was followed by a painful unconditioned stimulus (pain-US) and a rewarding unconditioned stimulus (reward-US) on 50% of the trials, whereas the other movement (nonreinforced conditioned stimulus [CS-]) movement was not. In the control condition, the CS+ movement was followed by the pain-US only. Results showed that pain-related fear was elevated in response to the CS+ compared to the CS- movement, but that it was not influenced by the reward-US. Interestingly, participants initiated a CS+ movement slower than a CS- movement in the control condition but not in the experimental condition. Also, in choice trials, participants performed the CS+ movement more frequently in the experimental than in the control condition. These results suggest that the presence of a valued competing goal can attenuate avoidance behavior. ⋯ The current study provides experimental evidence that both pain and competing goals impact on behavioral decision making and avoidance behavior. These results provide experimental support for treatments of chronic pain that include an individual's pursuit of valuable daily life goals, rather than limiting focus to pain reduction only.