[1] Med Univ Varna, Fac Publ Hlth, Varna, Bulgaria
[2] Med Univ Varna, Fac Med, Varna, Bulgaria
[3] Med Univ Varna, Coll Med, Varna, Bulgaria
[4] Natl Ctr Publ Hlth & Anal, Hlth Promot & Dis Prevent Directorate, Sofia, Bulgaria
[5] Bulgarian Publ Hlth Assoc, Pleven, Bulgaria
[6] Reg Hlth Inspectorate, Varna, Bulgaria
[7] Copenhagen Business Sch, MSc Business Adm & Innovat, Copenhagen, Denmark
[8] Med Univ Pleven, Fac Pharm, Pleven, Bulgaria