Footnotes

• Twitter Follow Miguel A. Martínez-González at @MAM_UNAV and Miguel Ruiz-Canela at @mruizcanela

• Contributors Both authors contributed equally to the writing of this work. MAM-G and MR-C had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Acquisition, analysis, or interpretation of data: MAM-G and MR-C. Drafting of the manuscript: MAM-G and MR-C. Critical revision of the manuscript for important intellectual content: both authors. Preparation of Table and Figure: MR-C. Administrative, technical or material support: MAM-G.

• Competing interests None declared.

• Provenance and peer review Commissioned; internally peer reviewed.