Pain
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Randomized Controlled Trial
A deeper look at pain variability and its relationship with the placebo response: results from a randomized, double-blind, placebo-controlled clinical trial of naproxen in osteoarthritis of the knee.
Previous studies have shown a robust correlation between variability of clinical pain scores and responsiveness to placebo (but not active drug) in pain studies, but explanations for these relationships are lacking. We investigated this further by assessing relationship between the Focused Analgesia Selection Test (FAST), a psychophysical method that quantifies pain reporting variability in response to experimental stimuli, variability of daily clinical pain scores as captured using diary, and response to treatment in the context of a randomized controlled crossover trial of naproxen vs placebo in knee osteoarthritis. Evoked pain using the Staircase-Evoked Pain Procedure served as the primary efficacy endpoint. ⋯ Both correlated with the placebo response (r = 0.393, P = 0.004; r =-0.371, P = 0.009; respectively), but only the FAST predicted the treatment difference between naproxen and placebo, as demonstrated both in a regression model (P = 0.002, Beta = 0.456, t = 3.342) and in a receiver operating characteristic curve (0.721) analysis. Our results extend previous findings to include a correlation between experimental pain variability and the placebo response and suggest that experimental pain variability is a better predictor of patients who respond preferentially to drug over placebo. A theoretical model unifying these observations is proposed, and practical implications are discussed.
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Randomized Controlled Trial
Can a brief psychological expectancy intervention improve postoperative pain? A randomized, controlled trial in patients with breast cancer.
Articulating positive expectations of analgesia efficacy preoperatively improves postoperative pain scores and analgesia satisfaction.
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Randomized Controlled Trial
Efficacy and safety of loxoprofen sodium topical patch for the treatment of pain in patients with minor acute traumatic limb injuries in Brazil: a randomized, double-blind, non-inferiority trial.
Posttraumatic injury pain is commonly treated with oral nonsteroidal anti-inflammatory drugs. However, oral nonsteroidal anti-inflammatory drugs cause several adverse events, with topical formulations arising as an important alternative. Therefore, we aimed at evaluating the efficacy and safety of loxoprofen patch (LX-P) in the treatment of patients with posttraumatic pain. ⋯ On the safety analysis, the LX-T group presented twice as many patients with treatment-emergent adverse events as the LX-P group (30.8% and 14.2%, respectively). A sensitivity analysis demonstrated that rescue medication use has not affected the primary end point. This study showed that LX-P has a comparable efficacy to LX-T, but with a better safety profile, being a therapeutic option for the treatment of posttraumatic injury pain.
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Randomized Controlled Trial
The role of afferent input in postamputation pain: a randomized, double-blind, placebo-controlled crossover study.
In this randomized, double-blind, placebo-controlled crossover study, we investigated whether a peripheral nerve block could temporarily eliminate phantom and stump pain after amputation. Amputees with constant postamputation pain were included and randomized to receive a nerve block with lidocaine 2% with adrenaline or saline in a crossover design. Spontaneous phantom and stump pain and evoked responses were assessed at baseline and at fixed time-points until 120 minutes after lidocaine or saline injection. ⋯ Phantom pain intensity was significantly reduced after lidocaine compared with saline injection (P = 0.04), whereas there was no significant change in stump pain intensity between the 2 interventions (P = 0.17). In all 9 amputees, evoked responses were eliminated after lidocaine injection. Thus, our findings suggest that afferent input from the peripheral nervous system plays an important role in postamputation pain.
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Randomized Controlled Trial
Summit-07: A randomized trial of NKTR-181, a new molecular entity, full mu-opioid receptor agonist for chronic low-back pain.
NKTR-181, a new molecular entity, mu-opioid receptor agonist with an inherently slow rate of central nervous system (CNS) entry, was designed to provide analgesia while reducing abuse potential. This phase 3, enriched-enrollment, randomized-withdrawal trial evaluated the analgesic efficacy, safety, and tolerability of NKTR-181 in patients with chronic low-back pain (CLBP). Adults with moderate-to-severe CLBP refractory to nonopioid analgesics achieving an analgesic NKTR-181 dosage (100-400 mg twice daily) during the open-label titration period were randomized to continued NKTR-181 treatment, double-blind, or switched to placebo. ⋯ The ≥30%-improvement responder rate of NKTR-181 vs placebo was 71.2% vs 57.1% (P < 0.001), and the ≥50%-improvement responder rate was 51.1% vs 37.9% (P = 0.001). NKTR-181 was well tolerated with a low incidence (<3%) of CNS-related adverse events during the randomized treatment phase. In patients with moderate-to-severe CLBP, NKTR-181 demonstrated significant analgesic efficacy and a favorable safety/tolerability profile, with a low incidence of CNS adverse events.