AI 中文总结
该研究提出对称配对匹配设计（SPM），一种自动调整时间效应的自我对照方法，利用事件前后观察时间保留更多信息，模拟显示其在时间趋势下无偏且效率更高，为瞬时暴露的观察性研究提供实用方案。
AI 中文摘要
自我对照研究设计可消除观察期内个体层面恒定特征导致的混杂，因此广泛应用于药物流行病学和疫苗安全性研究。然而，现有方法易受时间效应（包括暴露或结局的时间趋势和季节性）影响，除非通过研究设计明确建模或控制这些效应。我们提出对称配对匹配设计（SPM），一种新型自我对照方法，结合了基于设计的时间效应调整与时间不变混杂的自动控制。与之前仅使用事件发生前时间来解释时间效应的基于设计的方法不同，SPM同时利用事件发生前后的观察时间，从而保留了更大比例的可用信息。我们推导了该方法的理论性质，并通过模拟评估其有限样本性能。在模拟中，当结局和暴露均存在时间趋势时，SPM产生无偏估计，同时保持比现有方法更高或相当的统计效率。SPM通过基于设计的时间效应控制扩展了自我对照方法家族，无需对时间效应进行明确建模。通过结合对时间混杂的稳健性与观察时间的高效利用，SPM为具有瞬时暴露的观察性研究提供了实用替代方案。附带提供了R包以促进其在应用研究中的使用。
英文摘要
Self-controlled study designs eliminate confounding by individual-level characteristics that remain constant during the observation time and are thus widely used in pharmacoepidemiology and vaccine safety research. However, existing methods remain vulnerable to time effects, including temporal trends and seasonality in the exposure or outcome, unless these are explicitly modeled or controlled through the study design. We introduce the symmetric pair matching design (SPM), a novel self-controlled method that combines design-based adjustment for time effects with automatic control of time-invariant confounding. Unlike previous design-based approaches that account for time effects, SPM uses observation time both before and after event occurrence, thereby retaining a larger proportion of the available information. We derive the theoretical properties of the method and evaluate its finite-sample performance through simulations. In the simulations, SPM produced unbiased estimates in the presence of temporal trends in both the outcome and exposure, while maintaining greater or comparable statistical efficiency than existing approaches. SPM extends the family of self-controlled methods by providing design-based control of time effects without requiring explicit modeling thereof. By combining robustness to temporal confounding with efficient use of observation time, SPM offers a practical alternative for observational studies with transient exposures. An accompanying R package is provided to facilitate its usage in applied research.
