Department of Neurology and Neurology Research Unit, Odense University Hospital and University of Southern Denmark, Odense, Denmark.
Department of Clinical Medicine, Danish Pain Research Center, Aarhus University, Aarhus, Denmark.
Pain. 2022 Mar 1;163(3):483-488. doi: 10.1097/j.pain.0000000000002374.
Large placebo responses often negatively affect randomized controlled trials within the pain area. Understanding different possible factors that influence the placebo response is therefore important. In this retrospective analysis, we hypothesized that a large variability in baseline pain score would predict a greater placebo response and analyzed the impact of the coefficient of variation, SD, and difference between the highest and lowest numeric rating scale (NRS) score at baseline on the placebo response. A total of 160 observations on placebo response from 3 controlled clinical trials with a crossover design were included in this study. In general, the placebo response was low with a mean reduction in pain intensity of 0.5 points (range -5 to 7) measured on a 0 to 10 point NRS, and only 15% were placebo responders as defined by more than 30% reduction in NRS pain score from baseline to the end of the placebo treatment period. We found no significant impact of baseline pain coefficient of variation, SD, or the difference between lowest and highest baseline pain score on the placebo response. Placebo response in one trial did not predict placebo response in another trial. A large placebo response was not associated with a large treatment response. In conclusion, in this retrospective data analysis, there was no impact of baseline pain variability on the placebo response in controlled clinical trials with a crossover design in patients with peripheral neuropathic pain.
大的安慰剂反应常对疼痛领域的随机对照试验产生负面影响。因此，了解影响安慰剂反应的不同可能因素非常重要。在这项回顾性分析中，我们假设基线疼痛评分的较大变异性将预测更大的安慰剂反应，并分析了基线时变异系数、标准差和最高与最低数字评定量表 (NRS) 评分之间差异对安慰剂反应的影响。本研究共纳入了 3 项交叉设计的对照临床试验中 160 个安慰剂反应观察值。总体而言，安慰剂反应较低，疼痛强度平均降低 0.5 分（范围为-5 至 7），采用 0 至 10 分 NRS 进行测量，仅有 15%的患者被定义为安慰剂反应者，即 NRS 疼痛评分从基线到安慰剂治疗结束时降低超过 30%。我们发现基线疼痛变异系数、标准差或最低和最高基线疼痛评分之间的差异对安慰剂反应均无显著影响。一项试验中的安慰剂反应不能预测另一项试验中的安慰剂反应。大的安慰剂反应与大的治疗反应无关。总之，在这项回顾性数据分析中，在伴有周围神经性疼痛的交叉设计对照临床试验中，基线疼痛变异性对安慰剂反应没有影响。
