Saltaji Humam, Armijo-Olivo Susan, Cummings Greta G, Amin Maryam, Flores-Mir Carlos
Orthodontic Graduate Program, School of Dentistry, University of Alberta, Edmonton, Alberta, Canada.
BMJ Open. 2014 Feb 25;4(2):e004527. doi: 10.1136/bmjopen-2013-004527.
It is fundamental that randomised controlled trials (RCTs) are properly conducted in order to reach well-supported conclusions. However, there is emerging evidence that RCTs are subject to biases which can overestimate or underestimate the true treatment effect, due to flaws in the study design characteristics of such trials. The extent to which this holds true in oral health RCTs, which have some unique design characteristics compared to RCTs in other health fields, is unclear. As such, we aim to examine the empirical evidence quantifying the extent of bias associated with methodological and non-methodological characteristics in oral health RCTs.
We plan to perform a meta-epidemiological study, where a sample size of 60 meta-analyses (MAs) including approximately 600 RCTs will be selected. The MAs will be randomly obtained from the Oral Health Database of Systematic Reviews using a random number table; and will be considered for inclusion if they include a minimum of five RCTs, and examine a therapeutic intervention related to one of the recognised dental specialties. RCTs identified in selected MAs will be subsequently included if their study design includes a comparison between an intervention group and a placebo group or another intervention group. Data will be extracted from selected trials included in MAs based on a number of methodological and non-methodological characteristics. Moreover, the risk of bias will be assessed using the Cochrane Risk of Bias tool. Effect size estimates and measures of variability for the main outcome will be extracted from each RCT included in selected MAs, and a two-level analysis will be conducted using a meta-meta-analytic approach with a random effects model to allow for intra-MA and inter-MA heterogeneity.
The intended audiences of the findings will include dental clinicians, oral health researchers, policymakers and graduate students. The aforementioned will be introduced to the findings through workshops, seminars, round table discussions and targeted individual meetings. Other opportunities for knowledge transfer will be pursued such as key dental conferences. Finally, the results will be published as a scientific report in a dental peer-reviewed journal.
为了得出有充分依据的结论，正确开展随机对照试验（RCT）至关重要。然而，越来越多的证据表明，由于此类试验的研究设计特征存在缺陷，随机对照试验容易出现偏差，可能高估或低估真实的治疗效果。与其他健康领域的随机对照试验相比，口腔健康随机对照试验具有一些独特的设计特征，目前尚不清楚这种情况在口腔健康随机对照试验中是否成立。因此，我们旨在研究量化口腔健康随机对照试验中与方法学和非方法学特征相关的偏差程度的实证证据。
我们计划进行一项元流行病学研究，将选取60项元分析（MA）作为样本，其中包括约600项随机对照试验。这些元分析将使用随机数表从口腔健康系统评价数据库中随机获取；如果它们至少包括五项随机对照试验，并研究与公认的牙科专业之一相关的治疗干预措施，则将被考虑纳入。如果所选元分析中确定的随机对照试验的研究设计包括干预组与安慰剂组或另一个干预组之间的比较，则随后将其纳入。将根据一些方法学和非方法学特征从所选元分析中纳入的试验中提取数据。此外，将使用Cochrane偏倚风险工具评估偏倚风险。将从所选元分析中纳入的每项随机对照试验中提取主要结局的效应量估计值和变异性测量值，并使用具有随机效应模型的元元分析方法进行两级分析，以考虑元分析内部和元分析之间的异质性。
研究结果的目标受众将包括牙科临床医生、口腔健康研究人员、政策制定者和研究生。将通过研讨会、讲座、圆桌讨论和有针对性的个人会议向上述人员介绍研究结果。还将寻求其他知识转移机会，如重要的牙科会议。最后，研究结果将作为科学报告发表在牙科同行评审期刊上。
