The CHICO study is funded by the National Institute for Health Research as part of the NHS. The funding stream is the Health Technology Assessment (ref: 16/31/98) funding stream. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health.

Sponsor: University of Bristol (ref: 2835)

Ethical approval: Research Ethics Committee (ref:REC: 18/LO/0345)

Trial registration: ISRCTN (ref: ISRCTN11405239)