Supplementary Table 2.

Research ethic approval

Group	Committee
Bonn	Ethics Review Board of the University of Bonn
Bristol	Frenchay Local Research Ethics committee, Bristol
Nottingham	Nottingham Research Committee 2 (NHS)
OPTIMA	Central Oxford Ethics Committee No 1656
Oviedo	Ethical Committee of the Hospital Central de Asturias
Rotterdam	Medical Ethical Committee of the Erasmus MC
Santander	Ethical Committee of the University Hospital “Marqués de Valdecilla”, Santander