1Methods Support Unit, Cochrane, London, UK
2Central Editorial Service, Cochrane, London, UK
3Methods Support Unit, Cochrane, London, UK; Department of Hygiene and Epidemiology, School of Medicine, University of Ioannina, Ioannina, Greece
4Methods Support Unit, Cochrane, London, UK; Department of Hygiene, Social and Preventive Medicine, and Medical Statistics, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece