[1] Aristotle Univ Thessaloniki, Dept Hyg & Epidemiol, Med Sch, Univ Campus, Thessaloniki 54124, Greece
[2] Aristotle Univ Thessaloniki, Clin Res & Evidence Based Med Unit, Med Dept 2, Konstantinoupoleos 49, Thessaloniki 54642, Greece
[3] Univ Oxford, Harris Manchester Coll, Mansfield Rd, Oxford OX1 3TD, England
[4] Univ Ioannina, Sch Med, Dept Hyg & Epidemiol, Univ Campus,Stavros Niarchos Av, Ioannina, Greece
[5] Brown Univ, Sch Publ Hlth, Dept Hlth Serv Policy & Practice, Ctr Evidence Synth Hlth, 121 South Main St, Providence, RI 02903 USA