About the Authors

Corresponding Author

gakidou@u.washington.edu

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

EG, SN, and ZO designed the analytical framework. SN performed statistical analyses. EG, SN, and ZO drafted the manuscript. EG accepts full responsibility for the work and the conduct of the study, had access to the data, and controlled the decision to publish.