Antiviral therapy and outcomes of influenza requiring hospitalization in Ontario, Canada.
BACKGROUND
We conducted a prospective cohort study to assess the impact of antiviral therapy on outcomes of patients hospitalized with influenza in southern Ontario, Canada.


METHODS
Patients admitted to Toronto Invasive Bacterial Diseases Network hospitals with laboratory-confirmed influenza from 1 January 2005 through 31 May 2006 were enrolled in the study. Demographic and medical data were collected by patient and physician interview and chart review. The main outcome evaluated was death within 15 days after symptom onset.


RESULTS
Data were available for 512 of 541 eligible patients. There were 185 children (<15 years of age), none of whom died and none of whom were treated with antiviral drugs. The median age of the 327 adults was 77 years (range, 15-98 years), 166 (51%) were male, 245 (75%) had a chronic underlying illness, and 216 (71%) had been vaccinated against influenza. Of the 327 adult patients, 184 (59%) presented to the emergency department within 48 h after symptom onset, 52 (16%) required intensive care unit admission, and 27 (8.3%) died within 15 days after symptom onset. Most patients (292 patients; 89%) received antibacterial therapy; 106 (32%) were prescribed antiviral drugs. Treatment with antiviral drugs active against influenza was associated with a significant reduction in mortality (odds ratio, 0.21; 95% confidence interval, 0.06-0.80; n=100, 260). There was no apparent impact of antiviral therapy on length of stay in survivors.


CONCLUSIONS
There is a significant burden of illness attributable to influenza in this highly vaccinated population. Treatment with antiviral drugs was associated with a significant reduction in mortality.
McGeer
Allison
A
Toronto Medical Laboratories and Mount Sinai Hospital, Toronto, ON M5G 1X5 Canada. amcgeer@mtsinai.on.ca
Green
Karen A
KA
Plevneshi
Agron
A
Shigayeva
Altynay
A
Siddiqi
Nilofar
N
Raboud
Janet
J
Low
Donald E
DE
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000998:Antiviral Agents / Q000627:therapeutic use*; D002648:Child; D015331:Cohort Studies; D005260:Female; D006760:Hospitalization; D006801:Humans; D007251:Influenza, Human / Q000188:drug therapy* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D009864:Ontario; D011159:Population Surveillance; D011446:Prospective Studies; D016896:Treatment Outcome
D000998:Antiviral Agents