Pain
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Facial expressions of pain have been identified in several animal species. The aim of this systematic review was to provide evidence on the measurement properties of grimace scales for pain assessment. The protocol was registered (SyRF#21-November-2019), and the study is reported according to the PRISMA guidelines. ⋯ Reliability and other forms of validity have been understudied. This systematic review identified gaps in knowledge on the measurement properties of grimace scales. Further studies should focus on improving psychometric testing, instrument refinement, and the use of grimace scales for pain assessment in nonhuman mammals.
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Randomized Controlled Trial
Cannabidiol treatment in hand osteoarthritis and psoriatic arthritis: a randomized, double-blind placebo-controlled trial.
Cannabidiol (CBD) is increasingly used as analgesic medication although the recent International Association for the Study of Pain Presidential Task Force on cannabis and cannabinoid analgesia found a lack of trials examining CBD for pain management. This trial examines CBD as add-on analgesic therapy in patients with hand osteoarthritis or psoriatic arthritis experiencing moderate pain intensity despite therapy. Using a randomized, double-blind, placebo-controlled design, patients received synthetic CBD 20 to 30 mg or placebo daily for 12 weeks. ⋯ Twenty-two percent patients receiving CBD and 21% receiving placebo experienced a reduction in pain intensity of more than 30 mm. We found neither clinically nor statistically significant effects of CBD for pain intensity in patients with hand osteoarthritis and psoriatic arthritis when compared with placebo. In addition, no statistically significant effects were found on sleep quality, depression, anxiety, or pain catastrophizing scores.
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A number of studies have demonstrated substantial individual differences in placebo effects. We aimed to identify individual psychological factors that potentially predicted the magnitude of placebo hypoalgesia and individual responsiveness. The Research Domain Criteria framework and a classical conditioning with suggestions paradigm were adopted as experimental models to study placebo phenotypes in a cohort of 397 chronic pain participants with a primary diagnosis of temporomandibular disorder (TMD) and 397 healthy control (HC) participants. ⋯ A greater level of emotional distress was a significant predictor of smaller magnitude (slope b = -0.07) and slower extinction rate (slope b = 0.51) of placebo effects in both TMD and HC participants. Greater reward seeking was linked to greater postconditioning expectations (ie, reinforced expectations) in TMD (slope b = 0.16), but there was no such a prediction in HC participants. These findings highlight that negative valence systems might play a role in impairing placebo effects, with a larger impact in chronic pain participants than in healthy participants, suggesting that individuals reporting emotional distress and maladaptive cognitive appraisals of pain may benefit less from placebo effects.
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Chronic pain clinical trials have historically assessed benefit and risk outcomes separately. However, a growing body of research suggests that a composite metric that accounts for benefit and risk in relation to each other can provide valuable insights into the effects of different treatments. Researchers and regulators have developed a variety of benefit-risk composite metrics, although the extent to which these methods apply to randomized clinical trials (RCTs) of chronic pain has not been evaluated in the published literature. ⋯ A primary recommendation is that composite metrics of benefit-risk should be combined at the level of the individual patient, when possible, in addition to the benefit-risk assessment at the treatment group level. Both levels of analysis (individual and group) can provide valuable insights into the relationship between benefits and risks associated with specific treatments across different patient subpopulations. The systematic assessment of benefit-risk in clinical trials has the potential to enhance the clinical meaningfulness of RCT results.