Pre-and post-pandemic trends in antiviral use in hospitalized patients with laboratory-confirmed influenza: 2004/05-2013/14, Toronto, Canada.
Data on factors associated with the use of antiviral medication to treat influenza in both children and adults are limited.



To describe trends in antiviral use, analyze factors associated with antiviral treatment of hospitalized patients with influenza, and to compare use based on guidelines.



A retrospective observational cohort of hospitalized patients with laboratory confirmed influenza in southern Ontario hospitals for the 2004/05-2013/14 seasons.



Of the 7967 patients, 18% of the 1779 children (<15 years) and 66% of the 6188 adults received antiviral therapy. The percentage treated increased from 29% pre-pandemic to 74% during the pandemic, decreased to 55% in 2011/12 and then increased to 65% in 2013/14. Factors significantly associated with antiviral prescription across all age groups during the non-pandemic seasons include influenza type, disease severity, interval between symptom onset and test sample submission, and clinician suspicion of influenza. Rate of treatment of patients meeting guideline criteria was low for children and moderate for adults.



Since the pandemic, there has been a sustained increase in the use of antiviral medication for all age groups of hospitalized patients with influenza, but much higher for adults than children. The odds of treatment are higher for patients with more severe disease as well as for those tested within 48 h of symptom onset, both of which are part of the guidelines for treatment with anti-influenza medications.
Sinai Health System, 600 University Avenue, Toronto, ON M5G1X5, Canada; University of Toronto, 155 College Street, Toronto, ON M5T3M7, Canada. Electronic address: Brenda.coleman@sinaihealthsystem.ca.
Brenda L
BL
Coleman
Sinai Health System, 600 University Avenue, Toronto, ON M5G1X5, Canada.
Kazi
K
Hassan
Sinai Health System, 600 University Avenue, Toronto, ON M5G1X5, Canada.
Karen
K
Green
Public Health Ontario Laboratories, 661 University Ave., Toronto, ON M5G1M1, Canada; University of Toronto, 155 College Street, Toronto, ON M5T3M7, Canada.
Jonathan B
JB
Gubbay
North York General Hospital, 4001 Leslie St., North York, ON M2K1E1, Canada; University of Toronto, 155 College Street, Toronto, ON M5T3M7, Canada.
Kevin
K
Katz
Sinai Health System, 600 University Avenue, Toronto, ON M5G1X5, Canada; University of Toronto, 155 College Street, Toronto, ON M5T3M7, Canada.
Tony
T
Mazzulli
Canadian Centre for Vaccinology, IWK Health Centre, 5850/5980 University Ave., Halifax, NS B3K6R8, Canada; Dalhousie University, 6299 South St, Halifax, NS B3H4R2, Canada.
Shelly
S
McNeil
St. Michael's Hospital, 30 Bond St., Toronto, ON M5B1W8, Canada; University of Toronto, 155 College Street, Toronto, ON M5T3M7, Canada.
Matthew
M
Muller
Michael Garron Hospital, 825 Coxwell Ave., East York, ON M4C3E7, Canada; William Osler Health System, 2100 Bovaird Dr. E., Brampton, ON L6R3J7, Canada.
Jeff
J
Powis
William Osler Health System, 2100 Bovaird Dr. E., Brampton, ON L6R3J7, Canada.
David
D
Richardson
Sunnybrook Health Sciences Centre, 2075 Bayview Ave., Toronto, ON M4N3M5, Canada; University of Toronto, 155 College Street, Toronto, ON M5T3M7, Canada.
Andrew
A
Simor
Sinai Health System, 600 University Avenue, Toronto, ON M5G1X5, Canada; University of Toronto, 155 College Street, Toronto, ON M5T3M7, Canada.
Allison J
AJ
McGeer
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000998:Antiviral Agents / Q000627:therapeutic use*; D002170:Canada / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006760:Hospitalization; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification; D007251:Influenza, Human / Q000175:diagnosis / Q000188:drug therapy* / Q000453:epidemiology* / Q000821:virology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D058873:Pandemics; D012189:Retrospective Studies; D012307:Risk Factors; D012621:Seasons; D055815:Young Adult
D000998:Antiviral Agents
Hospital patients; Influenza; Neuraminidase inhibitor; Post-pandemic; Predictors