Gentles Stephen J, Stacey Dawn, Bennett Carol, Alshurafa Mohamad, Walter Stephen D
Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
Syst Rev. 2013 Oct 21;2:95. doi: 10.1186/2046-4053-2-95.
There is considerable unexplained heterogeneity in previous meta-analyses of randomized controlled trials (RCTs) evaluating the effects of patient decision aids on the accuracy of knowledge of outcome probabilities. The purpose of this review was to explore possible effect modification by three covariates: the type of control intervention, decision aid quality and patients' baseline knowledge of probabilities.
A sub-analysis of studies previously identified in the 2011 Cochrane review on decision aids for people facing treatment and screening decisions was conducted. Additional unpublished data were requested from relevant study authors to maximize the number of eligible studies. RCTs (to 2009) comparing decision aids with standardized probability information to control interventions (lacking such information) and assessing the accuracy of patient knowledge of outcome probabilities were included. The proportions of patients with accurate knowledge of outcome probabilities in each group were converted into relative effect measures. Intervention quality was assessed using the International Patient Decision Aid Standards instrument (IPDASi) probabilities domain.
A main effects analysis of 17 eligible studies confirmed that decision aids significantly improve the accuracy of patient knowledge of outcome probabilities (relative risk = 1.80 [1.51, 2.16]), with considerable heterogeneity (87%). The type of control did not modify effects. Meta-regression suggested that the IPDASi probabilities domain score (reflecting decision aid quality) is a potential effect modifier (P = 0.037), accounting for a quarter of the variability (R² = 0.28). Meta-regression indicated the control event rate (reflecting baseline knowledge) is a significant effect modifier (P = 0.001), with over half the variability in ln(OR) explained by the linear relationship with log-odds for the control group (R² = 0.52); this relationship was slightly strengthened after correcting for the statistical dependence of the effect measure on the control event rate.
Patients' baseline level of knowledge of outcome probabilities is an important variable that explains the heterogeneity of effects of decision aids on improving accuracy of this knowledge. Greater relative effects are observed when the baseline proportion of patients with accurate knowledge is lower. This may indicate that decision aids are more effective in populations with lower knowledge.
在以往评估患者决策辅助工具对结果概率知识准确性影响的随机对照试验（RCT）的荟萃分析中，存在相当大的无法解释的异质性。本综述的目的是探讨三个协变量可能的效应修正作用：对照干预的类型、决策辅助工具的质量以及患者对概率的基线知识。
对先前在2011年Cochrane关于面临治疗和筛查决策的人群决策辅助工具综述中确定的研究进行亚分析。向相关研究作者索要额外的未发表数据，以最大化符合条件的研究数量。纳入了将决策辅助工具与标准化概率信息进行比较以对照干预措施（缺乏此类信息）并评估患者对结果概率知识准确性的RCT（截至2009年）。将每组中对结果概率有准确知识的患者比例转换为相对效应量。使用国际患者决策辅助工具标准工具（IPDASi）概率领域评估干预质量。
对17项符合条件的研究进行的主效应分析证实，决策辅助工具显著提高了患者对结果概率知识的准确性（相对风险=1.80[1.51，2.16]），存在相当大的异质性（87%）。对照类型未改变效应。元回归表明，IPDASi概率领域得分（反映决策辅助工具质量）是一个潜在的效应修正因素（P = 0.037），占变异性的四分之一（R² = 0.28）。元回归表明，对照事件率（反映基线知识）是一个显著的效应修正因素（P = 0.001），ln(OR)中超过一半的变异性由与对照组对数优势的线性关系解释（R² = 0.52）；在纠正效应量对对照事件率的统计依赖性后，这种关系略有加强。
患者对结果概率的基线知识水平是一个重要变量，它解释了决策辅助工具对提高该知识准确性影响的异质性。当具有准确知识的患者基线比例较低时，观察到更大的相对效应。这可能表明决策辅助工具在知识水平较低的人群中更有效。
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