Ann Intern Med. 2015 Sep 1;163(5):365-72. doi: 10.7326/M15-0623.
Placebo controls are essential in evaluating the effectiveness of medical treatments. Although it is unclear whether different placebo interventions for osteoarthritis vary in efficacy, systematic differences would substantially affect interpretation of the results of placebo-controlled trials.
To evaluate the effects of alternative placebo types on pain outcomes in knee osteoarthritis.
MEDLINE, EMBASE, Web of Science, Google Scholar, and Cochrane Database from inception through 1 June 2015 and unpublished data.
149 randomized trials of adults with knee osteoarthritis that reported pain outcomes and compared widely used pharmaceuticals against oral, intra-articular, topical, and oral plus topical placebos.
Study data were independently double-extracted; study quality was assessed by using the Cochrane risk of bias tool.
Placebo effects that were evaluated by using a network meta-analysis with 4 separate placebo nodes (differential model) showed that intra-articular placebo (effect size, 0.29 [95% credible interval, 0.09 to 0.49]) and topical placebo (effect size, 0.20 [credible interval, 0.02 to 0.38]) had significantly greater effect sizes than did oral placebo. This differential model showed marked differences in the relative efficacies and hierarchy of the active treatments compared with a network model that considered all placebos equivalent. In the model accounting for differential effects, intra-articular and topical therapies were superior to oral treatments in reducing pain. When these differential effects were ignored, oral nonsteroidal anti-inflammatory drugs were superior.
Few studies compared different placebos directly. The study could not decisively conclude whether disease severity and co-interventions systematically differed between trials evaluating different placebos.
All placebos are not equal, and some can trigger clinically relevant responses. Differential placebo effects can substantially alter estimates of the relative efficacies of active treatments, an important consideration for the design of clinical trials and interpretation of their results.
Agency for Healthcare Research and Quality.
在评估医学治疗效果时，安慰剂对照至关重要。虽然尚不清楚针对骨关节炎的不同安慰剂干预措施在疗效上是否存在差异，但系统差异会极大地影响安慰剂对照试验结果的解释。
评估膝关节骨关节炎中替代安慰剂类型对疼痛结局的影响。
从建库至 2015 年 6 月 1 日，我们检索了 MEDLINE、EMBASE、Web of Science、Google Scholar 和 Cochrane 数据库，还检索了未发表的数据。
共纳入 149 项针对膝关节骨关节炎成人患者的随机试验，这些研究均报告了疼痛结局，并将广泛使用的药物与口服、关节内、局部和口服加局部安慰剂进行了比较。
研究数据由两名研究人员独立进行双份提取；使用 Cochrane 偏倚风险工具评估研究质量。
使用具有 4 个单独安慰剂节点的网络荟萃分析（差异模型）评估了安慰剂效应，结果显示关节内安慰剂（效应大小 0.29[95%可信区间 0.09 至 0.49]）和局部安慰剂（效应大小 0.20[可信区间 0.02 至 0.38]）的效应显著大于口服安慰剂。与将所有安慰剂视为等效的网络模型相比，该差异模型显示，与活性治疗相关的相对疗效和等级存在显著差异。在考虑到差异效应的模型中，关节内和局部治疗在减轻疼痛方面优于口服治疗。当忽略这些差异效应时，口服非甾体抗炎药的疗效则更佳。
很少有研究直接比较不同的安慰剂。该研究无法确定评估不同安慰剂的试验在疾病严重程度和合并干预方面是否存在系统差异。
并非所有安慰剂都一样，有些安慰剂可能会引发具有临床意义的反应。差异安慰剂效应会极大地改变对活性治疗相对疗效的估计，这是临床试验设计和结果解释的一个重要考虑因素。
美国卫生保健研究与质量署。
