Pain
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Randomized Controlled Trial
Side effects can enhance treatment response through expectancy effects: an experimental analgesic randomized controlled trial.
In randomized controlled trials, medication side effects may lead to beliefs that one is receiving the active intervention and enhance active treatment responses, thereby increasing drug-placebo differences. We tested these hypotheses with an experimental double-blind randomized controlled trial of a nonsteroidal anti-inflammatory drug with and without the addition of atropine to induce side effects. One hundred healthy volunteers were told they would be randomized to either combined analgesics that might produce dry mouth or inert placebos. ⋯ A chain of mediation analysis demonstrated that the addition of atropine increased dry mouth symptoms, which increased beliefs that one had received the active medication, which, in turn, increased analgesia. In addition to this indirect effect of atropine on analgesia (via dry mouth and beliefs), analyses suggest that among those who received diclofenac, atropine directly increased analgesia. This possible synergistic effect between diclofenac and atropine might warrant future research.
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A primary goal in managing pain is to reduce pain and increase physical function (PF). This goal is also tied to continuing payment for treatment services in many practice guidelines. Pain interference (PI) is often used as a proxy for measurement and reporting of PF in these guidelines. ⋯ A parallel process latent growth curve model analysis showed a weak, unidirectional relationship (β = 0.18) between average PF scores and changes in PI over the course of 90 days of care, and no relationship between average PI scores and changes in PF across time. Although PI and PF seem moderately related when measured concurrently, they do not cluster closely together across time. The differential pathways between these 2 domains suggest that therapies that target both the consequences of pain on relevant aspects of persons' lives, and capability to perform physical activities are likely required for restoration of a vital life.
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The prediction of acute postoperative pain would be of great clinical advantage, but results of studies investigating possible predictors are inconsistent. Here, we studied the role of a wide variety of previously suggested predictors in 74 patients undergoing breast surgery. Preoperatively, patients filled out the Pain Sensitivity Questionnaire (PSQ) and a set of psychological questionnaires (the Beck Depression Inventory [BDI], State-Trait Anxiety Inventory [STAI], and Pain Catastrophizing Scale [PCS]) and participated in an experimental pain testing session, including assessment of conditioned pain modulation (CPM), temporal summation, and responses to heat, pinprick, and pressure pain. ⋯ In conclusion, prediction of acute postoperative pain in the whole group was limited. This might be due to differing predictors in specific subgroups of patients. Although CPM predicted pain in patients without pre-existing chronic pain, PSQ and PCS predicted pain in patients with pre-existing chronic pain.