The journal of pain : official journal of the American Pain Society
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Optimal methods to predict risk of aberrant drug-related behaviors before initiation of opioids for chronic noncancer pain and to identify aberrant behaviors after therapy is initiated are uncertain. We systematically reviewed published literature identified through searches of Ovid MEDLINE and the Cochrane databases through July 2008. Diagnostic test characteristics and accompanying confidence intervals were calculated with data extracted from the studies. Four prospective studies evaluated diagnostic accuracy of risk prediction instruments. Two higher-quality derivation studies found that high scores on the Screener and Opioid Assessment for Patients with Pain (SOAPP) Version 1 and the Revised SOAPP (SOAPP-R) instruments weakly increased the likelihood for future aberrant drug-related behaviors (positive likelihood ratios [PLR], 2.90 [95% CI, 1.91 to 4.39] and 2.50 [95% CI, 1.93 to 3.24], respectively). Low scores on the SOAPP Version 1 moderately decreased the likelihood for aberrant drug-related behaviors (negative likelihood ratio [NLR], 0.13 [95% CI, 0.05 to 0.34]) and low scores on the SOAPP-R weakly decreased the likelihood (NLR, 0.29 [95% CI, 0.18 to 0.46]), but estimates are too imprecise to determine if there is a difference between these instruments. One lower-quality study found that categorization as high risk using the Opioid Risk Tool strongly increased the likelihood for future aberrant drug-related behaviors (PLR, 14.3 [95% CI, 5.35 to 38.4]) and classification as low risk strongly decreased the likelihood (PLR, 0.08 [95% CI, 0.01 to 0.62]). Nine studies evaluated monitoring instruments for identification of aberrant drug-related behaviors in patients on opioid therapy. One higher-quality derivation study found higher scores on the Current Opioid Misuse Measure (COMM) weakly increased the likelihood of current aberrant drug-related behaviors (PLR, 2.77 [95% CI, 2.06 to 3.72]) and lower scores weakly decreased the likelihood (NLR, 0.35 [95% CI, 0.24 to 0.52]). In 8 studies of other monitoring instruments, diagnostic accuracy was poor, results were difficult to interpret due to methodological shortcomings, or standard diagnostic test characteristics were not reported. Definitions for aberrant drug-related behaviors were not standardized across studies and did not account for seriousness of identified behaviors. No reliable evidence exists on accuracy of urine drug screening, pill counts, or prescription drug monitoring programs; or clinical outcomes associated with different assessment or monitoring strategies. ⋯ Evidence on prediction and identification of aberrant drug-related behaviors is limited. Although several screening instruments may be useful, evidence is sparse and primarily based on derivation studies, and methodological shortcomings exist in all studies. Research that performs external validation, uses standardized definitions for clinically relevant aberrant drug-related behaviors, and evaluates clinical outcomes associated with different assessment and monitoring strategies is needed.
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Randomized Controlled Trial
Diclofenac potassium attenuates dysmenorrhea and restores exercise performance in women with primary dysmenorrhea.
We assessed the efficacy of diclofenac potassium, a nonsteroidal anti-inflammatory drug, in alleviating menstrual pain and restoring exercise performance to that measured in the late-follicular phase of the menstrual cycle. Twelve healthy young women with a history of primary dysmenorrhea completed, in a random order, laboratory exercise-testing sessions when they were in the late-follicular (no menstruation, no pain) phase of the menstrual cycle and when they were experiencing dysmenorrhea and receiving, in a double-blinded fashion, either 100 mg of diclofenac potassium or placebo. We assessed the women's leg strength (1-repetition maximum test), aerobic capacity (treadmill walking test), and ability to perform a functional test (task-specific test). Compared with placebo, diclofenac potassium significantly decreased dysmenorrhea on the day of administration (Visual Analog Scale, P < .001 at all times). When receiving placebo for menstrual pain, the women's performance in the tests was decreased significantly, compared with when they were receiving diclofenac potassium for menstrual pain (P < .05) and compared with when they were in the late-follicular phase of the menstrual cycle (P < .05 for treadmill test, P < .01 for task-specific test and 1-repetition maximum test). Administration of diclofenac potassium for menstrual pain restored exercise performance to a level not different from that achieved in the late-follicular phase of the cycle. ⋯ In women with primary dysmenorrhea, menstrual pain, if untreated, decreases laboratory-assessed exercise performance. A recommended daily dose of a readily available nonsteroidal anti-inflammatory drug, diclofenac potassium, is effective in relieving menstrual pain and restoring physical performance to levels achieved when the women were in the late-follicular (no menstruation, no pain) phase of the menstrual cycle.
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Multicenter Study Comparative Study
Does the Neonatal Facial Coding System differentiate between infants experiencing pain-related and non-pain-related distress?
The Neonatal Facial Coding System (NFCS) is widely accepted as a measure of infant pain-related distress in known pain-specific contexts. It has clearly shown the ability to distinguish between facial reactivity in no-pain and pain-related situations. The primary purpose of this study was to explore whether NFCS differentiates between pain-related and non-pain-related distress. Two groups of 35 infants (1 group was distressed before injection whereas the other group was not distressed before injection) were coded using NFCS before and after an immunization procedure. Within-group analyses of infants who were distressed before immunization suggested that NFCS was not able to discriminate between pain-related and non-pain-related distress. However, between-group analyses showed NFCS discriminated between potential gradations of distress in infants after immunization. Results suggest that NFCS has the ability to discriminate between intensities of distress but not between pain-related and non-pain-related distress. ⋯ Adding to the NFCS validity literature, this study suggests that while able to distinguish between no-distress and pain-related distress, facial actions of NFCS may not distinguish between pain-related and non-pain-related distress expressions. However, NFCS was able to discern infants presumed to have higher pain-related distress due to experiencing pre-needle distress.
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Multicenter Study Clinical Trial
A single-blind, placebo run-in study of duloxetine for activity-limiting osteoarthritis pain.
Osteoarthritis pain is a significant problem for our aging population. Antidepressants that are serotonin-norepinephrine reuptake inhibitors are effective for other forms of chronic pain and may provide a new treatment option for osteoarthritis pain. We performed a single-blind, placebo run-in trial of 60 to 90 mg of duloxetine in 25 subjects with activity-limiting osteoarthritis pain. Each subject received 2 weeks of placebo followed by 10 weeks of duloxetine. The primary outcome was reduction in average pain intensity between 2 and 12 weeks for subjects completing the trial. Average pain on the Brief Pain Inventory (BPI) was 5.7 at baseline, 4.8 after the 2-week placebo run-in, and 3.5 at 12 weeks for the 17 patients completing the trial (28% decrease between 2 and 12 weeks, P = .122). Eight of 15 study completers who had nonmissing BPI results (53%) reported at least 30% pain reduction between weeks 2 and 12. The Western Ontario McMaster Osteoarthritis Index (WOMAC) pain score at baseline was 2.3, 1.8 after 2 weeks, and 1.3 after 12 weeks (30% decrease between 2 and 12 weeks, P = .018). Ten of 17 patients (59%) reported at least 30% pain relief between weeks 2 and 12 on the WOMAC. Significant improvements in self-reported physical and role function were reported but observed physical function did not improve. ⋯ Duloxetine did not significantly reduce pain intensity on the BPI but did improve pain intensity and self-reported function on the WOMAC. Duloxetine warrants further investigation as a novel treatment for osteoarthritis pain.
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Clinical Trial
Associations between catastrophizing and endogenous pain-inhibitory processes: sex differences.
Pain catastrophizing is among the most robust predictors of pain outcomes, and a disruption in endogenous pain-inhibitory systems is 1 potential mechanism that may account for increased pain among individuals who report higher pain catastrophizing. Pain catastrophizing may negatively influence diffuse noxious inhibitory controls (DNIC), a measure of endogenous pain inhibition, through complex anatomical circuitry linking cortical responses to pain with processes that modulate pain. The current study examined whether DNIC mediated the relationship between catastrophizing and pain among 35 healthy young adults and examined the moderating effects of sex to determine whether the magnitude or direction of associations differed among men and women. DNIC was assessed using pressure pain thresholds on the forearm before and during a cold pressor task. Using bias-corrected bootstrapped confidence intervals, results showed that diminished DNIC was a significant partial mediator of the relation between greater pain-related catastrophizing and more severe pain ratings. Participant sex moderated these associations; higher catastrophizing predicted lower DNIC for men and women, however, the effect of catastrophizing on pain ratings was partially mediated by DNIC for women only. These findings further support the primary role of pain catastrophizing in modulation of pain outcomes. ⋯ These findings support the hypothesis that the heightened pain reported by individuals higher in pain catastrophizing may be related to a disruption in the endogenous modulation of pain, operationalized by assessing DNIC. Whether interventions that reduce pain catastrophizing affect pain outcomes via effects on DNIC is in need of investigation.