The journal of pain : official journal of the American Pain Society
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In order to disentangle the effects of drugs from placebo responses, several approaches have been used, such as a placebo run-in phase in which only placebo nonresponders, or poor responders, are considered for further randomization to either placebo or active treatment. This study is aimed at investigating the variability of placebo nonresponders obtained through the classical placebo run-in paradigm (group RUN) and through mismatch conditioning (group MIS), as done in our previous study. To do this, we simulated a real clinical trial in the laboratory, in which the placebo responders of both groups were discarded and the remaining nonresponders of both groups RUN and MIS were randomized to either continuing on placebo (groups RUN-P and MIS-P, respectively) or receiving topical 0.5% lidocaine (groups RUN-L and MIS-L, respectively) applied to the skin. ⋯ Therefore, we suggest reconsidering the validity and usefulness of placebo run-in protocols. PERSPECTIVE: Placebo nonresponders are sometime selected for further randomization to either placebo or active treatment. In this experimental study, which is a laboratory simulation of a clinical trial, we found that placebo nonresponders vary from day to day, thus questioning their validity as a methodological approach in clinical research.
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Socioeconomic Position (SEP) is a multidimensional construct encompassing education, income, occupation, and neighborhood distress, influencing chronic pain severity, interference, and duration. However, its impact on placebo analgesia, where reduced pain perception occurs due to treatment belief, remains understudied. Using a quasi-experimental approach, we investigated SEP's influence on placebo analgesia in 401 participants with temporomandibular disorder (TMD) and 400 pain-free individuals. ⋯ PERSPECTIVE: SEP significantly contributes to pain disparities. This quasi-experimental study demonstrates analogous placebo analgesia between chronic pain and pain-free individuals but finds lower placebo analgesia only among individuals with chronic pain and distressed SEP. This highlights a link between chronic pain, SEP, and impaired placebo effects, suggesting new avenues for research.
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Chronic pain affects ∼20% of the adult population and is associated with smoking. Smoking and pain worsen each other in the long term, but short-term temporal associations between smoking and pain throughout the day are unclear. Understanding these relationships may inform strategies for managing comorbid smoking and pain. ⋯ Further research is needed on interventions that combine tailored smoking cessation treatments and behavioral pain management strategies. PERSPECTIVE: This analysis of momentary data reported throughout the day by people with back pain who smoke revealed novel insights into short-term relationships between pain and smoking. Study results can inform future treatment development for individuals with chronic pain who smoke.