To examine the pain relief effects of comparators (placebos and untreated control groups) in hand osteoarthritis trials and the impact of contextual factors. We systematically searched PubMed, EMBASE and CENTRAL from inception to December 26, 2021. We included randomised controlled trials of people with hand osteoarthritis with a placebo or an untreated control group. We assessed the Risk of Bias with Cochrane Risk-of-Bias tool version 2. Each comparator was contrasted with a null-arm, imputed as having a zero change from baseline with the same standard deviation as the comparator. We combined the standardised mean differences with a random effects meta-analysis. The contextual factors’ effect was explored in meta-regression and stratified models with pain as the dependent variable. 84 trials (7262 participants) were eligible for quantitative synthesis, of which 76 (6462 participants) were eligible for the stratified analyses. Placebos were superior to their matched null-arms in relieving pain with an effect size of −0.51 (95% confidence interval −0.61 to −0.42), while untreated control groups were not. When analysing all comparators, blinded trial designs and low risk of bias were associated with higher pain relief compared to an open-label trial design and some concern or high risk of bias. The placebo response on pain for people with hand osteoarthritis was increased by appropriate blinding and a lower risk of bias assessment. Placebos were superior to a null-arm, while untreated control groups were not. Results emphasise the importance of using appropriate comparators in clinical trials. CRD42022298984

中文翻译：

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不同安慰剂和比较组对手部骨关节炎的疗效比较，探索背景因素的影响：随机试验的系统评价和荟萃分析


研究手部骨关节炎试验中比较组（安慰剂和未经治疗的对照组）的疼痛缓解效果以及背景因素的影响。我们系统地检索了 PubMed、EMBASE 和 CENTRAL，从最初到 2021 年 12 月 26 日。我们纳入了手部骨关节炎患者与安慰剂或未经治疗的对照组的随机对照试验。我们使用 Cochrane 偏倚风险工具版本 2 评估了偏倚风险。每个比较器都与零臂进行对比，被估算为与基线相比具有零变化，并且与比较器具有相同的标准差。我们将标准化平均差异与随机效应荟萃分析结合起来。在以疼痛为因变量的元回归和分层模型中探讨了背景因素的影响。 84 项试验（7262 名受试者）有资格进行定量综合，其中 76 项试验（6462 名受试者）有资格进行分层分析。安慰剂在缓解疼痛方面优于其匹配的无效臂，效果大小为-0.51（95%置信区间-0.61至-0.42），而未经治疗的对照组则不然。在分析所有比较者时，与开放标签试验设计和一些担忧或高偏倚风险相比，盲法试验设计和低偏倚风险与更高的疼痛缓解相关。通过适当的盲法和较低的偏倚评估风险，安慰剂对手部骨关节炎患者的疼痛反应有所增加。安慰剂优于无效组，而未经治疗的对照组则不然。结果强调了在临床试验中使用适当的比较器的重要性。 CRD42022298984