Adult Australia--epidemiology Bariatric Surgery--adverse effects Body Mass Index Comorbidity Female Follow-Up Studies Gastrectomy--adverse effects Gastric Bypass--adverse effects Gastroplasty--adverse effects Health Resources--statistics & numerical data Humans Laparoscopy--methods Length of Stay Male Middle Aged Operative Time Public Sector--statistics & numerical data Reoperation--statistics & numerical data Treatment Outcome Weight Loss--physiology