CAN TRIALS OF PHYSICAL TREATMENTS BE BLINDED - THE EXAMPLE OF TRANSCUTANEOUS ELECTRICAL NERVE-STIMULATION FOR CHRONIC PAIN
CAN TRIALS OF PHYSICAL TREATMENTS BE BLINDED - THE EXAMPLE OF TRANSCUTANEOUS ELECTRICAL NERVE-STIMULATION FOR CHRONIC PAIN
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DOI：
10.1097/00002060-199002000-00003
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发表时间：
1990-02-01
影响因子：
3
通讯作者：
RAMAMURTHY, S
中科院分区：
文献类型：
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作者：
DEYO, RA;WALSH, NE;RAMAMURTHY, S
治疗试验常常试图使病人和研究者对所接受治疗的真实性质“视而不见”，减少有意识或潜意识偏见的影响。在药物试验中，这是用安慰剂药片完成的，但在物理治疗试验中，盲法更成问题。这个问题出现在经皮神经电刺激（TENS）治疗慢性腰痛患者的临床试验中。纳入了几个研究设计特征来促进盲化：使用视觉上与真实单元相同的假TENS单元，排除具有先前TENS经验的潜在受试者，避免交叉设计和使用相同的访问频率，说明和电极放置的修改。受试者被要求不要与进行结果评估的临床医生讨论治疗方法。在试验结束时，患者和临床医生都被要求猜测实际的治疗任务。在真正的TENS组中，每个患者都认为该装置功能正常，但确定的程度各不相同。在假性TENS组中，84%的人也认为他们有功能单位，但他们的确定性明显低于积极治疗组。患者认知的差异不影响依从性，因为两组的辍学率、预约依从性、使用TENS的天数和每天使用TENS的持续时间相似。临床医生猜测治疗方法的正确率为61%（而不是预期的50%），再次表明盲法取得了部分成功。这些在盲法上的努力可能在一定程度上解释了TENS疗效的负面试验结果。我们的结论是，由于治疗的感觉差异和患者与审查员之间的意外沟通，完全盲化很难实现。尽管如此，物理治疗的试验可以用这里描述的技术实现部分盲化，并且盲化的成功可以在研究完成时用简单的问题来评估。
Therapeutic trials often attempt to “blind” patient and investigator to the true nature of treatments received, reducing the influences of conscious or subconscious prejudices. In drug trials, this is accomplished with placebo tablets, but blinding in trials of physical treatments is more problematic. This issue arose in a clinical trial of transcutaneous electrical nerve stimulation (TENS) for patients with chronic low back pain. Several study design features were incorporated to promote blinding: use of sham TENS units visually identical with real units, exclusion of potential subjects with previous TENS experience, avoidance of a crossover design and use of identical visit frequency, instructions and modifications in electrode placement. Subjects were asked not to discuss treatments with the clinicians who performed outcome assessments. Both patients and clinicians were asked to guess actual treatment assignments at the trial's end. Every patient in the true TENS group believed the unit was functioning properly, but the degree of certainty varied. In the sham TENS group, 84% also believed they had functioning units, but their certainty was significantly less than in the active treatment group. Differences in patient perceptions did not affect compliance, as the two groups had similar dropout rates, appointment compliance, days of TENS use and daily duration of TENS use. Clinicians guessed treatments correctly 61% of the time (as opposed to 50% expected by chance), again suggesting partial success in blinding. These efforts at blinding may partly explain the negative trial results for TENS efficacy. We conclude that complete blinding is difficult to achieve because of sensory difference in treatment and unintended communication between patient and examiner. Nonetheless, trials of physical treatments can achieve partial blinding with the techniques described here, and the success of blinding can be assessed with simple questions at study completion.