1. Department of Otorhinolaryngology, Universitas Sumatera Utara, Medan, North Sumatera, Indonesia
2. Department of Obstetrics and Gynecology, Universitas Sumatera Utara, Medan, North Sumatera, Indonesia
3. Department of Epidemiology training research advocacy and teaching, Universitas Sumatera Utara, Medan, North Sumatra, Indonesia