Instrumental variables II: instrumental variable application-in 25 variations, the physician prescribing preference generally was strong and reduced covariate imbalance.
Instrumental variables II: instrumental variable application-in 25 variations, the physician prescribing preference generally was strong and reduced covariate imbalance.
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DOI：
10.1016/j.jclinepi.2008.12.006
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发表时间：
2009-12
影响因子：
7.2
通讯作者：
Schneeweiss, Sebastian
中科院分区：
文献类型：
--
作者：
Rassen, Jeremy A.;Brookhart, M. Alan;Glynn, Robert J.;Mittleman, Murray A.;Schneeweiss, Sebastian
关键词：
工具变量（IV）是研究暴露的无混杂替代变量，可用于在存在未测量混杂因素的情况下估计因果效应。为了提供可靠一致的效应估计值，IV应有效且合理有力。医生处方偏好（PPP）是一种使用医生处方变化来预测药物治疗的IV。由于协变量不平衡的减少可能表明IV有效性增加，我们试图在两项队列研究中检查25种PPP IV制剂的协变量平衡和工具强度。我们应用PPP IV评估两组老年患者中抗精神病药物（APM）的使用和随后的死亡。我们改变了购买力平价的测量方法，并进行了队列限制和分层。我们用两阶段最小二乘回归对风险差异进行建模。第一阶段部分r2值表征了仪器的强度。Mahalanobis距离总结了多个协变量之间的平衡。部分r2范围为0.028 - 0.099。PPP通常缓解了非精神病相关患者特征的不平衡，两个队列的总体不平衡平均降低了36%（±40%）。在我们的研究环境中，PPP IV的25种制剂中的大多数是强IV，并导致许多变化中的不平衡大幅减少。力量和不平衡之间的关系是复杂的。
An instrumental variable (IV) is an unconfounded proxy for a study exposure that can be used to estimate a causal effect in the presence of unmeasured confounding. To provide reliably consistent estimates of effect, IVs should be both valid and reasonably strong. Physician prescribing preference (PPP) is an IV that uses variation in doctors' prescribing to predict drug treatment. As reduction in covariate imbalance may suggest increased IV validity, we sought to examine the covariate balance and instrument strength in 25 formulations of the PPP IV in two cohort studies. We applied the PPP IV to assess antipsychotic medication (APM) use and subsequent death among two cohorts of elderly patients. We varied the measurement of PPP, plus performed cohort restriction and stratification. We modeled risk differences with two-stage least square regression. First-stage partial r2 values characterized the strength of the instrument. The Mahalanobis distance summarized balance across multiple covariates. Partial r2 ranged from 0.028 to 0.099. PPP generally alleviated imbalances in nonpsychiatry-related patient characteristics, and the overall imbalance was reduced by an average of 36% (±40%) over the two cohorts. In our study setting, most of the 25 formulations of the PPP IV were strong IVs and resulted in a strong reduction of imbalance in many variations. The association between strength and imbalance was mixed.
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影响因子：
7.2
作者：
DEYO, RA;CHERKIN, DC;CIOL, MA
通讯作者：
CIOL, MA
影响因子：
8.4
作者：
Murray, Michael P.
通讯作者：
Murray, Michael P.
影响因子：
14.6
作者：
Schneeweiss, Sebastian;Setoguchi, Soko;Wang, Philip S.
通讯作者：
Wang, Philip S.
影响因子：
3.7
作者：
Angrist, JD;Imbens, GW;Rubin, DB
通讯作者：
Rubin, DB
影响因子：
--
作者：
Schneeweiss, Sebastian;Solomon, Daniel H.;Brookhart, M. Alan
通讯作者：
Brookhart, M. Alan