The journal of pain : official journal of the American Pain Society
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The measurement of withdrawal to experimenter-delivered mechanical stimuli (von Frey test) and to heat stimuli (radiant heat paw-withdrawal or Hargreaves' test) applied to the hind paws is ubiquitous in preclinical pain research, but no normative values for the most-common applications of these tests have ever been published. We analyzed a retrospective data set of withdrawal thresholds or latencies in 8,150 mice in which these measures were taken using replicate determinations, before and after injection of inflammatory substances or experimental nerve damage producing pain hypersensitivity, totaling 97,332 measurements. All mice were tested in the same physical laboratory over a 20-year period using similar equipment and procedures. ⋯ These factors are discussed, and we believe that these normative data will serve as a useful reference for expected values in preclinical pain testing. PERSPECTIVE: This article presents a retrospective analysis of a large data set of mouse von Frey and radiant heat paw-withdrawal (Hargreaves' test) measurements collected in a single laboratory over 20 years. In addition to serving as a normative guide, sources of variability are identified including genotype, tester, and sex.
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Review Randomized Controlled Trial
The impact of patient race, patient socioeconomic status, and cognitive load of physician residents and fellows on chronic pain care decisions.
Social stereotypes are more likely to influence decision-making under conditions of high cognitive load (ie, mental workload), such as in medical settings. We examined how patient race, patient socioeconomic status (SES), physician cognitive load, and physician implicit beliefs about race and SES differences in pain tolerance impacted physicians' pain treatment decisions. Physician residents and fellows (N = 120) made treatment decisions for 12 computer-simulated patients with back pain that varied by race (Black/White) and SES (low/high). ⋯ These findings shed light on physician cognitive load as a clinically-relevant factor in the context of pain care quality and equity. PERSPECTIVE: These findings highlight the clinical relevance of physician cognitive load (eg, mental workload) when providing pain care for diverse patients. This line of work can support the development of interventions to manage physician cognitive load and its impact on pain care, which may ultimately help reduce pain disparities.
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Pain intensity is the most commonly used outcome domain in pain clinical trials. To minimize the chances of type II error (ie, concluding that a treatment does not have beneficial effects, when in fact it does), the measure of pain intensity used should be sensitive to changes produced by effective pain treatments. Here we sought to identify the combination of pain intensity ratings that would balance the need for reliability and validity against the need to minimize assessment burden. ⋯ In conclusion, using data from 3 or 4 days of assessment may be the best practice. PERSPECTIVE: Composite scores made up of at least 3 days of pain ratings appear to be needed to maximize reliability and validity while minimizing the assessment burden. TRIAL REGISTRATION: clinicaltrials.gov NCT01800604.
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Complex Regional Pain Syndrome (CRPS) is a condition of chronic pain, predominantly affecting one limb. CRPS is characterised by motor changes including slowed or uncoordinated movements. Cognitive processes that drive movement planning and/or execution might contribute to these changes. ⋯ PERSPECTIVE: This article presents research investigating cognitive processes related to motor planning in Complex Regional Pain Syndrome (CRPS). Using an online object affordance paradigm, validated in pain-free controls, the authors found that people with CRPS showed intact object affordance effects in the affected and unaffected hand, suggesting unaltered motor planning. DATA AVAILABILITY: The experiment materials, data, pre-processing scripts, and analysis scripts can be found via Open Science Framework (https://osf.io/nc825/files/osfstorage).
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Although evidence supports the importance of pain-related thoughts (ie, cognitive content, or what people think) as predictors of pain and pain-related function, evidence regarding the role of cognitive processes (ie, how people think about pain, eg, by accepting pain, not making judgments about pain, or being absorbed by the pain experience) in adjustment to chronic pain is in its early stages. Using baseline data from a clinical trial of individuals with chronic low back pain (N = 327), the study aimed to increase knowledge regarding the associations between cognitive processes, pain intensity, pain interference, and depression. The results indicate that a number of cognitive processes are significantly related to pain intensity when controlling for catastrophizing, although the pattern of associations found was opposite to those anticipated. ⋯ Longitudinal and experimental studies to evaluate the causal nature of the associations identified are warranted. PERSPECTIVE: The study findings highlight the potential importance of cognitive process variables (ie, how people think) in adjustment to chronic pain. Research to evaluate cognitive processes as potential mechanism variables in pain treatment is warranted.