Overcoming obstacles in obtaining individual participant data for meta-analysis.

Individual participant data (IPD) is the backbone of scientific inquiry and important to a meta-analysis for a variety of reasons. It is therefore important to be able to access IPD, and yet, obstacles persist that make it difficult for meta-analysts, as well as interested primary study analysts, to obtain it. In this paper, we discuss the barriers to obtaining IPD via online repositories or contacting primary study authors and provide an example data sharing agreement that can be used to ameliorate a few of these issues. We also discuss the ethics of data sharing. The goal of this paper is to help meta-analysts anticipate these potential barriers at the outset of their studies and hopefully increase the likelihood of producing thorough IPD syntheses and foster collaborative partnerships with primary study researchers.