Footnotes

• Contributors IH, CH and JT performed the literature reviews and wrote drafts of sections. MCM commented about the final version. MB drafted the initial version and completed the final version. All authors contributed and approved the final version.

• Funding MB funded by Medical Research Council Clinician Scientist fellowship (MR/M008797/1).

• Competing interests MB reports outside the submitted work investigator, led grants from Pfizer and Roche Diagnostics and personal fees paid to Newcastle University from Novartis.

• Provenance and peer review Commissioned; externally peer reviewed.