Footnotes

• Twitter @EMARIANOMD, @elboghdadly

• Contributors MT helped design the study, collected data, drafted and revised the initial manuscript, reviewed and approved the submitted manuscript. ERM helped design the study, edited the figure, drafted and revised the initial manuscript, reviewed and approved the submitted manuscript. KE helped design the study, reviewed and approved the submitted manuscript. NME helped design the study, reviewed and approved the submitted manuscript. AK helped design the study, collected and analysed data, reviewed and approved the submitted manuscript. PC helped design the study, collected and analysed data, reviewed and approved the submitted manuscript. SCM helped design the study, collected data, analysed data, drafted and revised the initial manuscript, reviewed and approved the submitted manuscript.

• Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

• Disclaimer This material is the result of work supported with resources and the use of facilities at the VA Palo Alto Health Care System (Palo Alto, CA, USA). The contents do not represent the views of VA or the US Government.

• Competing interests None declared.

• Patient consent for publication Not required.

• Provenance and peer review Not commissioned; externally peer reviewed.