Pain
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Focused attention typically enhances neural nociceptive responses, reflected electroencephalographically as increased amplitude of pain-evoked event-related potentials (ERPs). Additionally, pain-evoked ERPs are attenuated by hypertension and baroreceptor activity, through as yet unclear mechanisms. There is indirect evidence that these two effects may interact, suggesting that baroreceptor-related modulation of nociception is more than a low-level gating phenomenon. ⋯ Cued stimuli were associated with larger P2 amplitude, but this effect was abolished for stimuli presented during baroreceptor activation. No cardiac timing effect was observed for un-cued stimuli. Taken together, these findings suggest a close integration of cognitive-affective aspects of expectancy and baroreceptor influences on pain, and as such may cast further light on mechanisms underlying mental and physiological contributions to clinical pain.
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Randomized Controlled Trial Multicenter Study
A multicenter, placebo-controlled, double-blind, multiple-crossover study of Fentanyl Pectin Nasal Spray (FPNS) in the treatment of breakthrough cancer pain.
This randomized, double-blind, crossover study assessed the efficacy and tolerability of a new rapid onset nasal fentanyl formulation (Fentanyl Pectin Nasal Spray; FPNS) for breakthrough cancer pain (BTCP). Eighty-three of 114 patients experiencing one to four BTCP episodes/day while taking ≥60 mg/day of oral morphine or equivalent successfully identified an effective dose of FPNS during a titration phase and entered a double-blind phase in which 10 BTCP episodes were treated with this effective dose (7) or placebo (3). Compared with placebo, FPNS significantly improved mean summed pain intensity difference (SPID) from 10 min (P<0.05) until 60 min (P<0.0001), including the primary endpoint at 30 min (P<0.0001). ⋯ Approximately 70% of patients were satisfied or very satisfied with the convenience and ease of use of FPNS. Only 5.3% of patients withdrew from treatment due to adverse events, no significant nasal effects were reported, and 87% of patients elected to continue open-label treatment post-study. In this short-term study, FPNS was safe, well tolerated, and rapidly efficacious for BTCP.
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The clinical diagnosis of Complex Regional Pain Syndrome (CRPS) is a dichotomous (yes/no) categorization necessary for clinical decision-making. However, such dichotomous diagnostic categories do not convey an individual's subtle and temporal gradations in severity of the condition, and have poor statistical power when used as an outcome measure in research. This study evaluated the validity and potential utility of a continuous type score to index severity of CRPS. ⋯ In an archival prospective dataset, increases in anxiety and depression from pre-surgical baseline to 4 weeks post-knee arthroplasty were found to predict significantly higher CSS at 6- and 12-month follow-up (p's<.05). Results indicate the CSS corresponds with and complements currently accepted dichotomous diagnostic criteria for CRPS, and support its validity as an index of CRPS severity. Its utility as an outcome measure in research studies is also suggested, with potential statistical advantages over dichotomous diagnostic criteria.
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Numbers-needed-to-treat (NNT) are useful for presenting treatment response, conveying the clinical relevance of results. NNTs are typically calculated at a landmark endpoint (end of trial), but often using the last observation carried forward (LOCF), which ignores patient discontinuations. We compared NNTs in chronic low back pain (CLBP) using three separate imputation methods, using data from two identical 12-week trials comparing etoricoxib 60 mg (N=210), 90 mg (N=212), and placebo (N=217). ⋯ Landmark NNTs at week 12 were generally similar or slightly lower (better) than those from a longitudinal approach, but results were inconsistent. Landmark analyses provide no information on response variability, as is obtained with longitudinal analysis. Outcome, imputation method, and reporting method are intimately connected and need to be considered alongside trial quality and validity to make sensible comparisons between treatments.
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Little is known about patients prescribed high doses of opioids to treat chronic non-cancer pain, though these patients may be at higher risk for medication-related complications. We describe the prevalence of high-dose opioid use and associated demographic and clinical characteristics among veterans treated in a VA regional healthcare network. Veterans with chronic non-cancer pain prescribed high doses of opioids (≥ 180 mg/day morphine equivalent; n=478) for 90+ consecutive days were compared to two groups with chronic pain: Traditional-dose (5-179 mg/day; n=500) or no opioid (n=500). ⋯ After controlling for demographic factors and VA facility, neuropathy, low back pain, and nicotine dependence diagnoses were associated with increased likelihood of high-dose prescriptions. High-dose patients frequently did not receive care consistent with treatment guidelines: there was frequent use of short-acting opioids, urine drug screens were administered to only 25.7% of patients in the prior year, and 32.0% received concurrent benzodiazepine prescriptions, which may increase risk for overdose and death. Further study is needed to identify better predictors of high-dose usage, as well as the efficacy and safety of such dosing.