Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands.
Department of Paediatrics, Diakonessenhuis, Utrecht, The Netherlands.
Pharmacoepidemiol Drug Saf. 2021 Jul;30(7):960-974. doi: 10.1002/pds.5258. Epub 2021 May 10.
Guidance reports for observational comparative effectiveness and drug safety research recommend implementing a new-user design whenever possible, since it reduces the risk of selection bias in exposure effect estimation compared to a prevalent-user design. The uptake of this guidance has not been studied extensively.
We reviewed 89 observational effectiveness and safety cohort studies published in six pharmacoepidemiological journals in 2018 and 2019. We developed an extraction tool to assess how frequently new-user and prevalent-user designs were reported to be implemented. For studies that implemented a new-user design in both treatment arms, we extracted information about the extent to which the moment of meeting eligibility criteria, treatment initiation, and start of follow-up were reported to be aligned.
Of the 89 studies included, 40% reported implementing a new-user design for both the study exposure arm and the comparator arm, while 13% reported implementing a prevalent-user design in both arms. The moment of meeting eligibility criteria, treatment initiation, and start of follow-up were reported to be aligned in both treatment arms in 53% of studies that reported implementing a new-user design. We provided examples of studies that minimized the risk of introducing bias due to unclear definition of time origin in unexposed participants, immortal time, or a time lag.
Almost half of the included studies reported implementing a new-user design. Implications of misalignment of study design origin were difficult to assess because it would require explicit reporting of the target estimand in original studies. We recommend that the choice for a particular study time origin is explicitly motivated to enable assessment of validity of the study.
观察性比较有效性和药物安全性研究的指导报告建议尽可能采用新用户设计，因为与惯用用户设计相比，它可以降低暴露效应估计中选择偏差的风险。但尚未广泛研究过这一指导原则的应用情况。
我们回顾了 2018 年和 2019 年在六本药物流行病学期刊上发表的 89 项观察性有效性和安全性队列研究。我们开发了一个提取工具，用于评估新用户和惯用用户设计的报告实施频率。对于在治疗组中均采用新用户设计的研究，我们提取了有关符合资格标准、治疗开始和随访开始的时间是否对齐的信息。
在纳入的 89 项研究中，40%报告在研究暴露组和对照组均采用了新用户设计，而 13%报告在两组中均采用了惯用用户设计。在报告采用新用户设计的研究中，有 53%报告治疗组的符合资格标准、治疗开始和随访开始的时间对齐。我们提供了一些研究示例，这些研究通过明确定义未暴露参与者的时间起点、避免无定义的时间起点（即“不朽时间”）和时间滞后，最大限度地降低了因时间起点定义不明确而引入偏倚的风险。
纳入的研究中有近一半报告采用了新用户设计。由于需要在原始研究中明确报告目标估计值，因此很难评估设计起源的不匹配的影响。我们建议明确说明选择特定研究时间起点的原因，以便评估研究的有效性。
