BACKGROUND Obtaining unbiased causal estimates from longitudinal observational data can be difficult due to exposure-affected time-varying confounding. The past decade has seen considerable development in methods for analysing such complex longitudinal data. However, the extent to which those methods have been implemented is unclear. This study describes and characterizes the state of the field in methods adjusting for exposure-affected time-varying confounding, and examines their use in the literature. METHODS We systematically reviewed the literature from 2000 to 2016 for studies adjusting for time-dependent confounding, including use of specific methods like inverse probability of treatment weighting (IPTW). Articles were coded based on the methods used and, for applied articles, the topic areas covered. RESULTS We screened 4239 abstracts, and subsequently reviewed 1100 articles, leaving 542 relevant articles in the analyses. The number of published articles increased from two in 2000, to 112 in 2016. This increase was primarily in applied articles using IPTW, which increased from one study in 2000, to 90 in 2016. Of the 432 studies with applications to observed data, 60.9% were on at least one of: HIV (30.6%), cardiopulmonary health (13.2%), kidney disease (11.8%) or mental health (10.0%). CONCLUSIONS There has been marked growth in reports addressing exposure-affected time-varying confounding. This was driven by work in a small number of topic areas, with other areas showing relatively little uptake. In addition, despite developments in more advanced methods such doubly robust techniques and estimation via machine learning, implementation has been largely concentrated on the simpler, yet potentially less robust, IPTW.

中文翻译：

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因果模型调整时变混杂-文献的系统综述。

背景技术由于暴露影响的时变混杂，从纵向观察数据获得无偏因果估计可能是困难的。在过去的十年中，用于分析此类复杂纵向数据的方法取得了长足的发展。但是，这些方法的实施程度尚不清楚。这项研究描述和表征了领域的状态，该方法针对暴露受时间变化的混杂因素进行了调整，并在文献中对其进行了研究。方法我们系统地回顾了2000年至2016年的文献，以进行针对时间依赖性混杂因素的调整研究，包括使用特定方法，如治疗加权加权的概率（IPTW）。根据使用的方法对文章进行编码，而对于应用文章，则覆盖所涉及的主题领域。结果我们筛选了4239个摘要，随后审查了1100篇文章，在分析中保留了542篇相关文章。已发表文章的数量从2000年的2篇增加到2016年的112篇。这一增长主要来自使用IPTW的应用文章，从2000年的一项研究增加到2016年的90篇。在432项应用到观测数据的研究中，60.9篇％的人至少接受以下一项护理：HIV（30.6％），心肺健康（13.2％），肾脏疾病（11.8％）或精神健康（10.0％）。结论有关受暴露影响的随时间变化的混杂问题的报告显着增长。这是由少数主题领域的工作推动的，而其他领域的应用则相对较少。此外，尽管开发了更先进的方法（例如，双重健壮的技术和通过机器学习进行估算），