对卫生服务研究和医学中工具变量模型头20年的选择性回顾。

A selective review of the first 20 years of instrumental variables models in health-services research and medicine.

作者信息

Cawley John

机构信息

a Department of Policy Analysis and Management , Cornell University , Ithaca , NY , USA , and School of Economics, University of Sydney , Sydney , Australia.

出版信息

J Med Econ. 2015;18(9):721-34. doi: 10.3111/13696998.2015.1043917. Epub 2015 May 21.

DOI:10.3111/13696998.2015.1043917

PMID:25899087

Abstract

BACKGROUND

The method of instrumental variables (IV) is useful for estimating causal effects. Intuitively, it exploits exogenous variation in the treatment, sometimes called natural experiments or instruments. This study reviews the literature in health-services research and medical research that applies the method of instrumental variables, documents trends in its use, and offers examples of various types of instruments.

METHODS

A literature search of the PubMed and EconLit research databases for English-language journal articles published after 1990 yielded a total of 522 original research articles. Citations counts for each article were derived from the Web of Science. A selective review was conducted, with articles prioritized based on number of citations, validity and power of the instrument, and type of instrument.

RESULTS

The average annual number of papers in health services research and medical research that apply the method of instrumental variables rose from 1.2 in 1991-1995 to 41.8 in 2006-2010. Commonly-used instruments (natural experiments) in health and medicine are relative distance to a medical care provider offering the treatment and the medical care provider's historic tendency to administer the treatment. Less common but still noteworthy instruments include randomization of treatment for reasons other than research, randomized encouragement to undertake the treatment, day of week of admission as an instrument for waiting time for surgery, and genes as an instrument for whether the respondent has a heritable condition.

CONCLUSION

The use of the method of IV has increased dramatically in the past 20 years, and a wide range of instruments have been used. Applications of the method of IV have in several cases upended conventional wisdom that was based on correlations and led to important insights about health and healthcare. Future research should pursue new applications of existing instruments and search for new instruments that are powerful and valid.

摘要

背景

工具变量法对于估计因果效应很有用。直观地说，它利用了治疗中的外生变异，有时也称为自然实验或工具。本研究回顾了健康服务研究和医学研究中应用工具变量法的文献，记录了其使用趋势，并提供了各类工具的示例。

方法

对PubMed和EconLit研究数据库进行文献检索，查找1990年后发表的英文期刊原创研究文章，共获得522篇原创研究文章。每篇文章的被引次数来自科学网。进行了选择性综述，根据被引次数、工具的有效性和效能以及工具类型对文章进行排序。

结果

健康服务研究和医学研究中应用工具变量法的论文年均数量从1991 - 1995年的1.2篇增至2006 - 2010年的41.8篇。健康和医学中常用的工具（自然实验）是到提供治疗的医疗服务提供者的相对距离以及医疗服务提供者进行该治疗的历史倾向。不太常见但仍值得注意的工具包括因研究以外的原因进行治疗随机化、随机鼓励接受治疗、入院星期几作为手术等待时间的工具以及基因作为受访者是否患有遗传疾病的工具。