Division of Treatment and Recovery Research , National Institute on Alcohol Abuse and Alcoholism, Bethesda, Maryland.
Alcohol Clin Exp Res. 2013 Dec;37(12):2128-37. doi: 10.1111/acer.12197. Epub 2013 Jul 24.
The placebo effect often undermines efforts to determine treatment effectiveness in clinical trials. A significant placebo response occurs in alcohol trials, but it is not well understood. The purpose of this study was to characterize the placebo response across multiple naltrexone and acamprosate studies.
Fifty-one trials, 3 with a naltrexone and an acamprosate arm, 31 with at least 1 naltrexone arm, and 17 with at least 1 acamprosate arm, were identified from Cochrane reviews and PubMed search. To be included in this study, patients had to be at least 18 years old, abstinent from alcohol before randomization, and meet a diagnosis of alcohol dependence. Pearson correlation coefficients (rp ) and simple linear regression were used to describe the strength of linear relationships between placebo response and treatment effect size. Spearman's rank correlation coefficients (rs ) were used to examine the strength of associations between study characteristics and placebo response.
For the end point measures of percent days abstinent and total abstinence, a negative relationship was evident between placebo response and treatment effect size in the naltrexone trials (rp = -0.55, p < 0.01 and rp = -0.20, p = 0.35, respectively) as well as in the acamprosate trials (rp = -0.45, p = 0.09 and rp = -0.56, p = 0.01, respectively). The placebo response for percent days abstinent was negatively correlated with mean age of participants (rs = -0.42, p = 0.05) across naltrexone trials and positively correlated with publication year (rs = 0.57, p = 0.03) across acamprosate trials. However, these 2 study characteristics were not significantly correlated with treatment effect size.
The placebo response varied considerably across trials and was negatively correlated with the treatment effect size. Additional studies are required to fully understand the complex nature of the placebo response and to evaluate approaches to minimize its effects.
安慰剂效应常常会削弱临床试验中对治疗效果的评估。在酒精试验中，会出现显著的安慰剂反应，但目前人们对此还缺乏了解。本研究旨在对多个纳曲酮和安非他酮试验中的安慰剂反应进行特征描述。
从 Cochrane 综述和 PubMed 检索中确定了 51 项试验，其中 3 项试验有纳曲酮和安非他酮组，31 项试验至少有 1 个纳曲酮组，17 项试验至少有 1 个安非他酮组。要纳入本研究，患者必须年满 18 岁，在随机分组前戒酒，并且符合酒精依赖的诊断标准。采用 Pearson 相关系数（rp）和简单线性回归来描述安慰剂反应和治疗效果大小之间的线性关系强度。采用 Spearman 秩相关系数（rs）来检验研究特征与安慰剂反应之间的关联强度。
对于戒酒天数百分比和完全戒酒的终点测量指标，纳曲酮试验中（rp=-0.55，p<0.01 和 rp=-0.20，p=0.35）以及安非他酮试验中（rp=-0.45，p=0.09 和 rp=-0.56，p=0.01），安慰剂反应与治疗效果大小呈负相关。纳曲酮试验中，参与者的平均年龄与戒酒天数百分比的安慰剂反应呈负相关（rs=-0.42，p=0.05），而安非他酮试验中，发表年份与安慰剂反应呈正相关（rs=0.57，p=0.03）。然而，这两个研究特征与治疗效果大小无显著相关性。
安慰剂反应在试验中差异很大，与治疗效果大小呈负相关。需要进一步研究以全面了解安慰剂反应的复杂性质，并评估减轻其影响的方法。
