About the Authors
Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
Harvard School of Public Health, Harvard University, Cambridge, Massachusetts, United States of America
The authors have declared that no competing interests exist.
Wrote the first draft of the manuscript: KH NW. Contributed to the writing of the manuscript: KH NW. ICMJE criteria for authorship read and met: NW KH FZ. Agree with manuscript results and conclusions: NW KH FZ. Conceived the analysis: NW. Collaborated on design of the analysis: KH. Performed the analysis: KH FZ. Analyzed the results: NW KH.