Use of instrumental variable in prescription drug research with observational data: a systematic review.

ABSTRACT:

Objective

Instrumental variable (IV) analysis may offer a useful approach to the problem of unmeasured confounding in prescription drug research if the IV is: (1) strongly and unbiasedly associated to treatment assignment; and (2) uncorrelated with factors predicting the outcome (key assumptions).

Study design and methods

We conducted a systematic review of the use of IV methods in prescription drug research to identify the major types of IVs and the evidence for meeting IV assumptions. We searched MEDLINE, OVID, PsychoInfo, EconLit, and economic databases from 1961 to 2009.

Results

We identified 26 studies. Most (n=16) were published after 2007. We identified five types of IVs: regional variation (n=8), facility-prescribing patterns (n=5), physician preference (n=8),

SUBMITTER: Chen Y 

PROVIDER: S-EPMC3079803 | biostudies-literature | 2011 Jun

REPOSITORIES: biostudies-literature