Laugesen Kristina, Støvring Henrik, Hallas Jesper, Pottegård Anton, Jørgensen Jens Otto Lunde, Sørensen Henrik Toft, Petersen Irene
Department of Clinical Epidemiology, Aarhus University Hospital.
Department of Public Health, Aarhus University, Aarhus.
Clin Epidemiol. 2017 Nov 16;9:591-600. doi: 10.2147/CLEP.S148671. eCollection 2017.
Glucocorticoids are widely used medications. In many pharmacoepidemiological studies, duration of individual prescriptions and definition of treatment episodes are important issues. However, many data sources lack this information. We aimed to estimate duration of individual prescriptions for oral glucocorticoids and to describe continuous treatment episodes using the parametric waiting time distribution.
We used Danish nationwide registries to identify all prescriptions for oral glucocorticoids during 1996-2014. We applied the parametric waiting time distribution to estimate duration of individual prescriptions each year by estimating the 80th, 90th, 95th and 99th percentiles for the interarrival distribution. These corresponded to the time since last prescription during which 80%, 90%, 95% and 99% of users presented a new prescription for redemption. We used the Kaplan-Meier survival function to estimate length of first continuous treatment episodes by assigning estimated prescription duration to each prescription and thereby create treatment episodes from overlapping prescriptions.
We identified 5,691,985 prescriptions issued to 854,429 individuals of whom 351,202 (41%) only redeemed 1 prescription in the whole study period. The 80th percentile for prescription duration ranged from 87 to 120 days, the 90th percentile from 116 to 150 days, the 95th percentile from 147 to 181 days, and the 99th percentile from 228 to 259 days during 1996-2014. Based on the 80th, 90th, 95th and 99th percentiles of prescription duration, the median length of continuous treatment was 113, 141, 170 and 243 days, respectively.
Our method and results may provide an important framework for future pharmacoepidemiological studies. The choice of which percentile of the interarrival distribution to apply as prescription duration has an impact on the level of misclassification. Use of the 80th percentile provides a measure of drug exposure that is specific, while the 99th percentile provides a sensitive measure.
糖皮质激素是广泛使用的药物。在许多药物流行病学研究中，个体处方的持续时间和治疗疗程的定义是重要问题。然而，许多数据来源缺乏此类信息。我们旨在估计口服糖皮质激素个体处方的持续时间，并使用参数化等待时间分布来描述连续治疗疗程。
我们利用丹麦全国性登记处识别1996年至2014年期间所有口服糖皮质激素的处方。我们应用参数化等待时间分布，通过估计到达间隔分布的第80、90、95和99百分位数来估计每年个体处方的持续时间。这些百分位数对应自上次处方以来的时间，在此期间，80%、90%、95%和99%的使用者开具了新的处方以供取药。我们使用Kaplan-Meier生存函数，通过为每个处方分配估计的处方持续时间来估计首个连续治疗疗程的长度，从而从重叠的处方中创建治疗疗程。
我们识别出向854,429名个体开具的5,691,985张处方，其中351,202人（41%）在整个研究期间仅取药1张处方。1996年至2014年期间，处方持续时间的第80百分位数范围为87至120天，第90百分位数为116至150天，第95百分位数为147至181天，第99百分位数为228至259天。基于处方持续时间的第80、90、95和99百分位数，连续治疗的中位数长度分别为113、141、170和243天。
我们的方法和结果可能为未来的药物流行病学研究提供重要框架。选择将到达间隔分布的哪个百分位数用作处方持续时间会对错误分类水平产生影响。使用第80百分位数可提供一种特定的药物暴露衡量方法，而第99百分位数提供一种敏感的衡量方法。
