About the Authors

Stefan Baral

Affiliations Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America , Center for Public Health and Human Rights, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America , Department of Public Health Sciences, University of Toronto, Toronto, Ontario, Canada

Frangiscos Sifakis

Affiliations Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America , Center for Public Health and Human Rights, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America

Farley Cleghorn

Affiliation Constella Futures Group, Washington, D.C., United States of America

Chris Beyrer

To whom correspondence should be addressed. E-mail: cbeyrer@jhsph.edu

Affiliations Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America , Center for Public Health and Human Rights, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

SB designed the initial search strategies and was one of the authors responsible for abstraction and data analysis. SB was also responsible for authoring the first draft of the manuscript. CB is SB's supervisor and was the source of the original ideas for this research study. CB was also responsible for abstraction and played a significant role in the writing of this manuscript. FS contributed critical thought, aided in data analysis, and also was responsible for authoring sections of the manuscript. FC helped direct the research, provided extensive critical review of the writing and data analysis methods.