Department of Internal Medicine, University Hospital of Ioannina, Ioannina, Greece. School of Medicine, European University of Cyprus, Nicosia, Cyprus. Evidence-Based Medicine Unit, Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, Ioannina, Greece. Clinical Research and Evidence-Based Medicine Unit, Aristotle University of Thessaloniki, Hippokration Hospital, Thessaloniki, Greece. Harris Manchester College, University of Oxford, Oxford, UK. Department of Medicine, Beth Isreal Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA. Section of Endocrinology, Boston VA Healthcare System, Harvard Medical School, Boston, Massachusetts, USA. Evidence-Based Medicine Unit, Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, Ioannina, Greece entzani@uoi.gr. Center for Evidence Synthesis in Health, Department of Health Services, Policy and Practice, School of Public Health, Brown University, Providence, Rhode Island, USA. Institute of Biosciences, University Research Center of loannina, University of Ioannina, Ioannina, Greece.