The journal of pain : official journal of the American Pain Society
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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.
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This investigation determined the psychometric properties and acceptability of an animated face scale presented on a hand-held computer as a means to measure pediatric pain and mood. In study 1, 79 hospitalized, pediatric patients indicated their levels of pain by adjusting the expression of an animated cartoon face. The first objective was to determine feasibility, concurrent validity, and acceptability of the method. All patients were tested both with the Computer Face Scale and the poster format of the Wong-Baker Faces Scale. A second objective was to evaluate test-retest reliability of the method. In study 2, 50 hospitalized, pediatric patients were tested on 2 occasions, but in this case the patients used the Computer Face Scale to indicate both their pain (how much they hurt) and their mood (how they felt). Children in study 1 were able to use the Computer Face Scale to express relative amounts of pain/hurt; the method showed concurrent validity with the Wong-Baker Face Scale; and most children expressed a preference for the Computer Face Scale. The method also showed adequate test-retest reliability. In study 2, adequate test-retest reliability was demonstrated for ratings of both pain and mood. ⋯ The Computer Face Scale allows the health provider to obtain reliable and valid measures of pediatric pain and mood. The method can be understood and used by children as young as 3 years and is appropriate for use with adults.
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Practice Guideline
Clinical guidelines for the use of chronic opioid therapy in chronic noncancer pain.
Use of chronic opioid therapy for chronic noncancer pain has increased substantially. The American Pain Society and the American Academy of Pain Medicine commissioned a systematic review of the evidence on chronic opioid therapy for chronic noncancer pain and convened a multidisciplinary expert panel to review the evidence and formulate recommendations. Although evidence is limited, the expert panel concluded that chronic opioid therapy can be an effective therapy for carefully selected and monitored patients with chronic noncancer pain. However, opioids are also associated with potentially serious harms, including opioid-related adverse effects and outcomes related to the abuse potential of opioids. The recommendations presented in this document provide guidance on patient selection and risk stratification; informed consent and opioid management plans; initiation and titration of chronic opioid therapy; use of methadone; monitoring of patients on chronic opioid therapy; dose escalations, high-dose opioid therapy, opioid rotation, and indications for discontinuation of therapy; prevention and management of opioid-related adverse effects; driving and work safety; identifying a medical home and when to obtain consultation; management of breakthrough pain; chronic opioid therapy in pregnancy; and opioid-related policies. ⋯ Safe and effective chronic opioid therapy for chronic noncancer pain requires clinical skills and knowledge in both the principles of opioid prescribing and on the assessment and management of risks associated with opioid abuse, addiction, and diversion. Although evidence is limited in many areas related to use of opioids for chronic noncancer pain, this guideline provides recommendations developed by a multidisciplinary expert panel after a systematic review of the evidence.
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Intraplantar injection of bee venom (BV) produces persistent spontaneous nociception (PSN) and hyperalgesia, as well as obvious inflammatory swelling, in the paws of injected rats. The present study was designed to determine the peripheral roles of mitogen-activated protein kinase (MAPK) signal transduction pathways in BV-induced nociception and inflammation. We examined the effect of intraplantar injection of an ERK1/2 inhibitor, PD98059, and a p38 inhibitor, SB202190, on BV-induced PSN, mechanical hyperalgesia, and inflammatory swelling. We found that (1) pretreatment with SB202190 (0.1 to 10 microg) had no effect on BV-induced PSN, whereas pretreatment with PD98059 (0.1 to 100 microg) produced a significant and dose-dependent inhibition of BV-induced PSN; (2) pretreatment with PD98059 (0.1 to 100 microg) had no effect on BV-induced decreases in paw withdrawal mechanical threshold (PWMT), while pretreatment with SB202190 (0.1 to 10 microg) produced an obvious prevention of the BV-induced decrease in PWMT; and (3) pretreatment with PD98059 (0.1 to 100 microg) had no effect on BV-induced increase in paw volume (PV), whereas pretreatment with SB202190 (0.1 to 10 microg) produced a dose-related inhibition of BV-induced increases in PV. No contralateral drug treatments, even at the highest dose, had any effect on BV-induced PSN, PWMT or PV, ruling out the systemic effect of these drugs. These results suggest that peripheral MAPK signal transduction pathways may play differential roles in bee venom-induced nociception and inflammation. Targeting specific peripheral MAPKs might prove effective in the treatment of persistent pain and inflammation. ⋯ The present article showed that intraplantar injection of different MAPK inhibitors produced differential effects on bee venom-induced nociception and inflammation, suggesting that the peripheral MAPK signal transduction pathways have differential roles. Targeting specific peripheral MAPKs might prove effective in the treatment of persistent pain and inflammation.