Finniss Damien, Nicholas Michael, Brooker Charles, Cousins Michael, Benedetti Fabrizio
Pain Management Research Institute, Royal North Shore Hospital, University of Sydney, Sydney, Australia.
Department of Anaesthesia, Royal North Shore Hospital, St Leonards, Australia.
Pain Rep. 2019 Jun 7;4(3):e744. doi: 10.1097/PR9.0000000000000744. eCollection 2019 May-Jun.
Denervation of the lumbar zygapophyseal joints by medial branch radiofrequency neurotomy has shown some benefit in treating chronic low-back pain. Before denervation, a diagnosis is made by one or more blinded injections on separate occasions to ascertain whether the relevant joints are contributing to the pain. Placebo injections have been advocated in a diagnostic regime that also includes local anaesthesia, with a decision to proceed to neurotomy based on response to local anaesthesia and not to placebo.
We investigated the magnitude of and response rate to placebo injections, and the roles of expectation, desire for pain relief, and anxiety as determinants of response to placebo.
One hundred twenty patients were randomised to receive placebo and local anaesthetic injections on alternate occasions in a double-blind manner. A smaller control group with 2 local anaesthetic injections was also used. Responses to placebo were characterised, including magnitude and frequency.
This study demonstrated very large response to placebo injections, both response rate (78%) and magnitude (effect size d = 1.85). Expectation and anxiety were important modulators of response to placebo in this setting, with support given to expectation as a dynamic modulator of placebo responses. Large response to placebo (both in rate and magnitude) was observed when participants reported the belief that they were in the placebo arm.
This study demonstrated large placebo responses in the context of injections for low-back pain and further characterised the importance of expectation and anxiety as important psychological mediators.
通过内侧支射频神经切断术对腰椎关节突关节进行去神经支配已显示出在治疗慢性下腰痛方面有一定益处。在去神经支配之前，通过在不同时间进行一次或多次盲法注射来做出诊断，以确定相关关节是否是疼痛的原因。在一种还包括局部麻醉的诊断方案中提倡使用安慰剂注射，根据对局部麻醉而非安慰剂的反应来决定是否进行神经切断术。
我们研究了安慰剂注射的程度和反应率，以及期望、缓解疼痛的愿望和焦虑作为安慰剂反应决定因素的作用。
120名患者被随机分组，以双盲方式在不同时间接受安慰剂和局部麻醉剂注射。还使用了一个较小的对照组，进行2次局部麻醉剂注射。对安慰剂的反应进行了特征描述，包括程度和频率。
本研究表明对安慰剂注射有非常大的反应，无论是反应率（78%）还是程度（效应大小d = 1.85）。在这种情况下，期望和焦虑是安慰剂反应的重要调节因素，支持期望作为安慰剂反应的动态调节因素。当参与者报告认为自己处于安慰剂组时，观察到对安慰剂有很大的反应（在率和程度上）。
本研究表明在注射治疗下腰痛的背景下有很大的安慰剂反应，并进一步描述了期望和焦虑作为重要心理调节因素的重要性。
