Pain and Placebo - a Study to Examine Relations Between Pain Reporting Accuracy and the Response to Experimental Placebo Model
试验速览
- 阶段
- 不适用
- 入组人数
- 100
- 试验地点
- 2
- 主要终点
- Pain reporting accuracy
研究概览
简要总结
Good clinical care relies on precise evaluation of patients' conditions. Chronic pain and other neurological and psychiatric diagnoses pose challenges because their assessment depends on subjective patient-reported outcome measures (PROs). The investigators have recently developed the Focused Analgesia Selection Task (FAST), a method that allows assessing pain reporting accuracy. Preliminary results suggest that those who more accurately report their pain show diminished placebo response. The underlying mechanisms for this observation cannot be explained by current theories. Therefore, the investigators have conducted a pilot study to further characterize this relation in healthy population.
详细描述
Instruments and procedures:
Instruments All stimuli were applied by a contact-heat Thermal Sen-sory Analyzer 2001 system (Medoc, Ramat-Yishai, Israel) with a 30 x 30mm Peltier surface stimulator, which was attached by Velcro straps to the volar surface of the forearm of the subjects' hand.
Familiarization session At the beginning of the experimental session, all subjects underwent short training in order to familiarize them with the device and with the sensations evoked by the painful stimulation, and to train them to report their perceived pain intensity using the numerical pain scale. The training included exposure to three short contact-heat stimuli (44, 46.5, and 48°C), each lasting for 7 seconds from the time that the stimulation intensity reached the destination temperature. The thermode was moved following each stimulus to a completely distinct, adjacent area of skin. Subjects were asked to report the numerical pain score (NPS), on a scale ranging from 0, denoting no pain, to 100, denoting the worst pain imaginable, induced by each stimulus.
Pain reporting accuracy assessment:
The subject's pain reporting accuracy skills was assessed by the FAST, which is based on recording a subject's pain reports in response to repeated administration of thermal noxious stimuli of various intensities. During the FAST procedure the thermode was attached to the ventral surface of the subject's non-dominant arm and the temperature was raised from a baseline of 32°C, peaked for 3 seconds at 1 of 7 designated temperatures (44°C, 45°C, 46°C, 47°C, 48°C, 49°C, and 50°C), and then decreased down to the baseline. Stimulus rate of rise and fall was kept constant at 8°C/seconds. Subjects were asked to rate the peak pain intensity of each stimulus verbally using the NPS. Each temperature was presented 7 times in a random block-ordered design (49 stimuli in total). Inter-stimulus intervals of 20 seconds allowed the subject sufficient time to rate the pain they perceived during each stimulus. The location of the thermode was adjusted every 10 stimuli to minimize sensitization and/or habituation effects. The duration of the FAST procedure is ~25 minutes.
研究设计
- 研究类型
- Interventional
- 分配方式
- Na
- 干预模型
- Single Group
- 主要目的
- Other
- 盲法
- None
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •absence of acute or chronic pain disorders;
- •no reports of psychiatric, cognitive and /or neurological disorders;
- •no drugs including, analgesics or anti-anxiety medications on regular use (except for oral contraceptives).
排除标准
- •pregnant or breast-feeding;
- •unable to give informed consent, communicate and understand the purpose and the instructions of the study.
研究组 & 干预措施
Study arm
Each subject underwent baseline assessment of pain reporting accuracy (FAST). Thereafter, the placebo response was assessed using tonic heat stimuli delivered at fixed temperature of 44, 46.5, and 48°C which evoke mild, moderate and severe pain sensations (in accordance). The stimuli were given in a pseudo-random order twice, once before receiving the placebo pill (a sugar pill) and once after, maintaining the same order as before.
干预措施: Placebo (Other)
结局指标
主要结局
Pain reporting accuracy
时间窗: Fast procedure itself (49 heat stimuli, from 7 designated heat temperatures, given in a random block-order design) lasting approximately 20 minutes.
Subjects will be asked to report their pain on numerical pain scale (NPS) ranging from 0, denoting "no pain", to 10, denoting "the worst pain imaginable".
Change in experimental pain perception due to placebo pill intake
时间窗: Tonic stimuli before the placebo (Pre-placebo) until receiving the same stimuli 20 minutes after taking the placebo pill (Post-placebo).
Subjects will be asked to report their pain on numerical pain scale (NPS) ranging from 0, denoting "no pain", to 10, denoting "the worst pain imaginable". The placebo effect (Δ) will be calculated as the difference between the mean NPS.
次要结局
未报告次要终点
研究者
Roi Treister
Head of The Clinical Pain Innovation Lab
University of Haifa