Department of Physical Therapy, Catholic University of Maule, Talca, Chile.
Physiotherapy. 2011 Dec;97(4):291-301. doi: 10.1016/j.physio.2011.01.001. Epub 2011 Feb 5.
(1) To determine the effect of active and placebo interferential current on muscle pain sensitivity using an experimental mechanically induced pain model. (2) To evaluate the predictive role of expectations, gender, baseline muscle pain sensitivity, and intervention order on placebo response.
Randomized placebo controlled cross-over trial.
University research laboratory.
Forty healthy volunteers (20 females, 20 males).
Active interferential current, placebo (sham) interferential current, and no treatment/control were applied to the lumbar area on different days.
Pressure pain thresholds and placebo response.
The two-way ANOVA with repeated measures analysis determined a significant interaction between condition and time (P=0.002). Pairwise comparisons found differences between active interferential and the control condition at 15 minutes into treatment (mean difference=0.890 kg/cm(2), 95% CI 0.023 to 1.757, P=0.043) and at 30 minutes into treatment (mean difference=0.910 kg/cm(2), 95% CI 0.078 to 1.742, P=0.028). The increase in pressure pain thresholds between the active interferential and the control condition (1.12 kg/cm(2)) was clinically meaningful. Logistic regression analysis showed that the condition sequence order was the only variable that predicted placebo response (odds ratio 9.7; P=0.028). If a subject started the sequence receiving placebo treatment first, the odds of responding to placebo would be approximately 10 times higher (i.e. 90% probability of being a placebo responder) than that of starting with an active treatment.
Active interferential was more efficient than control condition in decreasing muscle pain sensitivity. Placebo interferential was not significantly different from control. Treatment sequence demonstrated a strong association with placebo response. These findings have implications for future research characterizing and identifying placebo responders in physiotherapy.
（1）使用实验性机械诱发疼痛模型，确定主动和安慰剂干扰电流对肌肉疼痛敏感性的影响。（2）评估期望、性别、基线肌肉疼痛敏感性和干预顺序对安慰剂反应的预测作用。
随机安慰剂对照交叉试验。
大学研究实验室。
40 名健康志愿者（20 名女性，20 名男性）。
主动干扰电流、安慰剂（假）干扰电流和无治疗/对照在不同天应用于腰部。
压痛阈值和安慰剂反应。
重复测量两因素方差分析确定了条件和时间之间的显著交互作用（P=0.002）。两两比较发现，在治疗 15 分钟时，主动干扰电流与对照条件之间存在差异（平均差异=0.890 kg/cm(2)，95%CI 0.023 至 1.757，P=0.043），在治疗 30 分钟时存在差异（平均差异=0.910 kg/cm(2)，95%CI 0.078 至 1.742，P=0.028）。主动干扰电流和对照条件之间的压痛阈值增加（1.12 kg/cm(2)）具有临床意义。逻辑回归分析显示，条件序列顺序是唯一预测安慰剂反应的变量（优势比 9.7；P=0.028）。如果受试者首先接受安慰剂治疗，那么对安慰剂产生反应的几率大约是接受主动治疗的 10 倍（即 90%的可能性成为安慰剂反应者）。
主动干扰电流比对照条件更有效地降低肌肉疼痛敏感性。安慰剂干扰电流与对照条件无显著差异。治疗顺序与安慰剂反应具有很强的关联。这些发现对未来的研究具有启示意义，有助于在物理治疗中对安慰剂反应者进行特征描述和识别。
