title: A difference is a difference if it makes a difference.
authors.forename: M R
authors.initials: MR
authors.lastname: Tramèr
authors.forename: P
authors.initials: P
authors.lastname: Garnerin
mesh_terms: D015360:Analgesia, Epidural / Q000009:adverse effects*; D000701:Analgesics, Opioid / Q000009:adverse effects*; D006801:Humans; D015201:Meta-Analysis as Topic; D010149:Postoperative Pain / Q000188:drug therapy*; D001261:Pulmonary Atelectasis / Q000209:etiology*; D013223:Statistics as Topic
chemical_list: D000701:Analgesics, Opioid