About the Authors

Emma L. Anderson

emma.louise.anderson@bristol.ac.uk

Affiliations MRC Integrative Epidemiology Unit at the University of Bristol, Bristol, United Kingdom, School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom

Laura D. Howe

Affiliations MRC Integrative Epidemiology Unit at the University of Bristol, Bristol, United Kingdom, School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom

Hayley E. Jones

Affiliation School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom

Julian P. T. Higgins

Affiliations School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom, Centre for Reviews and Dissemination, University of York, York, United Kingdom

Debbie A. Lawlor

Affiliations MRC Integrative Epidemiology Unit at the University of Bristol, Bristol, United Kingdom, School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom

Abigail Fraser

Affiliations MRC Integrative Epidemiology Unit at the University of Bristol, Bristol, United Kingdom, School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: AF LDH DAL. Performed the experiments: ELA AF LDH DAL. Analyzed the data: ELA AF HEJ JPTH. Wrote the paper: ELA LDH DAL AF HEJ JPTH. Had the initial idea for the study: AF LDH DAL. Designed the study and wrote protocols of identifying studies, extracting data and completing analyses: AF LDH DAL ELA. Identified studies and abstracted data from all included studies: ELA. Acted as second independent abstractors, each abstracting from a different subset of studies: AF LDH DAL. Undertook all statistical analyses with supervision from AF and input from HEJ and JPTH: ELA. Wrote the first draft of the paper and coordinated comments from other co-authors: ELA. Made critical comments on earlier drafts and contributed to the writing of the final paper: ELA LDH DAL AF HEJ JPTH. Acted as guarantors: ELA AF.