title: Antivirals for influenza: a summary of a systematic review and meta-analysis of observational studies.
abstract: Despite the use of antivirals to treat patients with severe influenza, questions remain with respect to effects and safety. Although a recent systematic review has provided some indication of benefit, the analysis is limited by the quality of the available evidence from randomized controlled trials. To supplement the existing information, the authors conducted a systematic review of observational studies of antiviral treatment for influenza. This report summarises the findings of that review. Similar to the randomised trials, the confidence in the estimates of the effects for decision-making is low to very low primarily due to the risk of selection and publication bias in the observational studies. From these observational studies, the summary estimates suggest that oseltamivir may reduce mortality, hospitalisation and duration of symptoms compared with no treatment. Inhaled zanamivir may also reduce symptom duration and hospitalisations, but patients may experience more complications compared with no treatment. Earlier treatment with antivirals is generally associated with better outcomes than later treatment. Further high-quality evidence is needed to inform treatment guidelines because of the overall low to very low quality of evidence.
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
authors.forename: Nancy
authors.initials: N
authors.lastname: Santesso
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Hsu
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
authors.forename: Reem
authors.initials: R
authors.lastname: Mustafa
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
authors.forename: Jan
authors.initials: J
authors.lastname: Brozek
authors.affiliation: Evidence-Based Medicine Center, School of Basic Medical Sciences, Lanzhou University, Gansu, China.
authors.forename: Yao Long
authors.initials: YL
authors.lastname: Chen
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.|Niagara Region Public Health, Thorold, ON, Canada.
authors.forename: Jessica P
authors.initials: JP
authors.lastname: Hopkins
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
authors.forename: Adrienne
authors.initials: A
authors.lastname: Cheung
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
authors.forename: Gayane
authors.initials: G
authors.lastname: Hovhannisyan
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
authors.forename: Liudmila
authors.initials: L
authors.lastname: Ivanova
authors.affiliation: Norwegian Knowledge Centre for the Health Services, Oslo, Norway.|Department of Public Health and Primary Health Care, University of Bergen, Bergen, Norway.
authors.forename: Signe A
authors.initials: SA
authors.lastname: Flottorp
authors.affiliation: Norwegian Knowledge Centre for the Health Services, Oslo, Norway.
authors.forename: Ingvil
authors.initials: I
authors.lastname: Saeterdal
authors.affiliation: Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada.
authors.forename: Arthur D
authors.initials: AD
authors.lastname: Wong
authors.affiliation: Evidence-Based Medicine Center, School of Basic Medical Sciences, Lanzhou University, Gansu, China.
authors.forename: Jinhui
authors.initials: J
authors.lastname: Tian
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Uyeki
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.|Department of Medicine, State University of New York, Buffalo, NY, USA.
authors.forename: Elie A
authors.initials: EA
authors.lastname: Akl
authors.affiliation: Iberoamerican Cochrane Centre, CIBERESP-IIB Sant Pau, Barcelona, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Alonso-Coello
authors.affiliation: Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.
authors.forename: Fiona
authors.initials: F
authors.lastname: Smaill
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.|Department of Medicine, McMaster University, Hamilton, ON, Canada.
authors.forename: Holger J
authors.initials: HJ
authors.lastname: Schünemann
mesh_terms: D000998:Antiviral Agents / Q000009:adverse effects / Q000627:therapeutic use*; D064420:Drug-Related Side Effects and Adverse Reactions / Q000453:epidemiology; D006801:Humans; D007251:Influenza, Human / Q000188:drug therapy*; D053139:Oseltamivir / Q000009:adverse effects / Q000627:therapeutic use*; D016019:Survival Analysis; D016896:Treatment Outcome; D053243:Zanamivir / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D000998:Antiviral Agents; D053139:Oseltamivir; D053243:Zanamivir
keywords: M2 ion channel blocker; antiviral; influenza; neuraminidase inhibitor; observational study
references.citation: Bone Marrow Transplant. 2003 Apr;31(8):695-700
references.pmid: 12692610
references.citation: Clin Infect Dis. 2010 Feb 15;50(4):621-2
references.pmid: 20095841
references.citation: Ann Acad Med Singap. 2010 Apr;39(4):283-8
references.pmid: 20473452
references.citation: Pediatrics. 2009 Jul;124(1):170-8
references.pmid: 19564297
references.citation: J Infect Dis. 2009 Aug 15;200(4):492-500
references.pmid: 19591575
references.citation: PLoS Med. 2010 May 18;7(5):e1000277
references.pmid: 20502525
references.citation: Clin Infect Dis. 2006 Aug 15;43(4):439-44
references.pmid: 16838232
references.citation: PLoS One. 2009 Jun 25;4(6):e6051
references.pmid: 19557130
references.citation: Sov Med. 1980;(9):103-4
references.pmid: 7423248
references.citation: Clin Infect Dis. 2007 Jan 15;44(2):197-202
references.pmid: 17173216
references.citation: BMJ. 2010 Sep 28;341:c4779
references.pmid: 20876641
references.citation: Pediatr Infect Dis J. 2009 Jul;28(7):647-8
references.pmid: 19483663
references.citation: Emerg Infect Dis. 2009 Jan;15(1):19-23
references.pmid: 19116044
references.citation: Medscape J Med. 2008 Jun 04;10(6):131
references.pmid: 18679536
references.citation: J Infect. 2010 Feb;60(2):168-74
references.pmid: 20036689
references.citation: Clin Ther. 2002 Nov;24(11):1824-39
references.pmid: 12501877
references.citation: Pediatr Infect Dis J. 2010 Oct;29(10):898-904
references.pmid: 20442686
references.citation: MedGenMed. 2007 Oct 30;9(4):23
references.pmid: 18311373
references.citation: BMJ. 2008 Apr 26;336(7650):924-6
references.pmid: 18436948
references.citation: Clin Infect Dis. 2005 May 1;40(9):1309-16
references.pmid: 15825034
references.citation: Clin Infect Dis. 2008 Aug 1;47(3):339-45
references.pmid: 18582202
references.citation: Am J Respir Crit Care Med. 2010 Jul 1;182(1):41-8
references.pmid: 20203241
references.citation: MMWR Morb Mortal Wkly Rep. 2010 Jan 8;58(51):1436-40
references.pmid: 20057350
references.citation: J Infect. 2008 Jan;56(1):51-7
references.pmid: 17936910
references.citation: BMC Infect Dis. 2010 Aug 27;10:256
references.pmid: 20799934
references.citation: Curr Med Res Opin. 2005 May;21(5):761-8
references.pmid: 15969875
references.citation: Euro Surveill. 2009 Jul 23;14(29):
references.pmid: 19643052
references.citation: Clin Infect Dis. 2007 Apr 1;44(7):964-7
references.pmid: 17342649
references.citation: Circ Cardiovasc Qual Outcomes. 2009 Mar;2(2):108-15
references.pmid: 20031822
references.citation: Clin Infect Dis. 2007 Dec 15;45(12):1568-75
references.pmid: 18190317
references.citation: Zh Mikrobiol Epidemiol Immunobiol. 1983 Mar;(3):60-3
references.pmid: 6221493
references.citation: Tohoku J Exp Med. 2008 Feb;214(2):113-20
references.pmid: 18285668
references.citation: Chest. 2010 Apr;137(4):759-68
references.pmid: 20061398
references.citation: Thorax. 2010 Jun;65(6):510-5
references.pmid: 20522848
references.citation: Ann Intern Med. 2012 Apr 3;156(7):512-24
references.pmid: 22371849
references.citation: Clin Infect Dis. 2010 Apr 1;50(7):963-9
references.pmid: 20180701
references.citation: Cochrane Database Syst Rev. 2010 Feb 17;(2):CD001265
references.pmid: 20166059
references.citation: Clin Infect Dis. 2009 Jun 15;48(12):1639-46
references.pmid: 19435433
references.citation: J Infect. 2009 Sep;59(3):207-12
references.pmid: 19619898
references.citation: JAMA. 2010 Apr 21;303(15):1517-25
references.pmid: 20407061
references.citation: Kansenshogaku Zasshi. 2003 Nov;77(11):971-6
references.pmid: 14672010