Using the waiting time distribution with random index dates to estimate prescription durations in the presence of seasonal stockpiling
Using the waiting time distribution with random index dates to estimate prescription durations in the presence of seasonal stockpiling
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DOI：
10.1002/pds.5026
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发表时间：
2020-05-21
影响因子：
2.6
通讯作者：
Stovring, Henrik
中科院分区：
文献类型：
--
作者：
Bodkergaard, Katrine;Selmer, Randi M.;Stovring, Henrik
目的在基于注册的药物流行病学研究中，一个普遍存在的问题是如何将暴露持续时间分配给个体处方。参数等待时间分布（WTD）已被提出作为一种方法来估计这样的持续时间。但是，当处方持续时间因季节性库存而变化时，WTD估计值将随索引日期的选择而变化。为了解决这个问题，我们建议使用随机索引dates.Methods在一个给定长度的日历周期内，delta，我们随机抽样个别索引日期。我们在分析中包括指数日期之前的最后一次处方赎回。仅包括指数日期的距离delta内的赎回。在一个模拟研究中，不同类型和程度的库存在年底，我们调查的偏差和精度的反向WTD与固定和随机指数日期，分别。结果在有库存的模拟环境中，采用随机索引日期的反向WTD具有较低的相对偏差（-0.65%至6.64%）和高覆盖概率（92.0%至95.3%），尽管当库存明显时，覆盖概率下降（2.7%至85.8%）。使用固定的索引日期是较差的。华法林处方在挪威使用随机索引日期的估计持续时间为131（130; 132）days.Conclusions在存在季节性囤积，WTD与随机索引日期提供了估计处方持续时间，这是更稳定，更少的偏见和更好的覆盖面相比，使用一个固定的索引日期。
Purpose A pervasive problem in registry-based pharmacoepidemiological studies is what exposure duration to assign to individual prescriptions. The parametric waiting time distribution (WTD) has been proposed as a method to estimate such durations. However, when prescription durations vary due to seasonal stockpiling, WTD estimates will vary with choice of index date. To counter this, we propose using random index dates.Methods Within a calendar period of a given length, delta, we randomly sample individual index dates. We include the last prescription redemption prior to the index date in the analysis. Only redemptions within distance delta of the index date are included. In a simulation study with varying types and degrees of stockpiling at the end of the year, we investigated bias and precision of the reverse WTD with fixed and random index dates, respectively. In addition, we applied the new method to estimate durations of Norwegian warfarin prescriptions in 2014.Results In simulation settings with stockpiling, the reverse WTD with random index dates had low relative biases (-0.65% to 6.64%) and high coverage probabilities (92.0% to 95.3%), although when stockpiling was pronounced, coverage probabilities decreased (2.7% to 85.8%). Using a fixed index date was inferior. The estimated duration of warfarin prescriptions in Norway using random index dates was 131 (130; 132) days.Conclusions In the presence of seasonal stockpiling, the WTD with random index dates provides estimates of prescription durations, which are more stable, less biased and with better coverage when compared to using a fixed index date.