Risk factors for SARS transmission from patients requiring intubation: a multicentre investigation in Toronto, Canada.
BACKGROUND
In the 2003 Toronto SARS outbreak, SARS-CoV was transmitted in hospitals despite adherence to infection control procedures. Considerable controversy resulted regarding which procedures and behaviours were associated with the greatest risk of SARS-CoV transmission.


METHODS
A retrospective cohort study was conducted to identify risk factors for transmission of SARS-CoV during intubation from laboratory confirmed SARS patients to HCWs involved in their care. All SARS patients requiring intubation during the Toronto outbreak were identified. All HCWs who provided care to intubated SARS patients during treatment or transportation and who entered a patient room or had direct patient contact from 24 hours before to 4 hours after intubation were eligible for this study. Data was collected on patients by chart review and on HCWs by interviewer-administered questionnaire. Generalized estimating equation (GEE) logistic regression models and classification and regression trees (CART) were used to identify risk factors for SARS transmission.


RESULTS
45 laboratory-confirmed intubated SARS patients were identified. Of the 697 HCWs involved in their care, 624 (90%) participated in the study. SARS-CoV was transmitted to 26 HCWs from 7 patients; 21 HCWs were infected by 3 patients. In multivariate GEE logistic regression models, presence in the room during fiberoptic intubation (OR = 2.79, p = .004) or ECG (OR = 3.52, p = .002), unprotected eye contact with secretions (OR = 7.34, p = .001), patient APACHE II score > or = 20 (OR = 17.05, p = .009) and patient Pa0(2)/Fi0(2) ratio < or = 59 (OR = 8.65, p = .001) were associated with increased risk of transmission of SARS-CoV. In CART analyses, the four covariates which explained the greatest amount of variation in SARS-CoV transmission were covariates representing individual patients.


CONCLUSIONS
Close contact with the airway of severely ill patients and failure of infection control practices to prevent exposure to respiratory secretions were associated with transmission of SARS-CoV. Rates of transmission of SARS-CoV varied widely among patients.
Raboud
Janet
J
Division of Infectious Diseases, University Health Network, Toronto, Ontario, Canada.
Shigayeva
Altynay
A
McGeer
Allison
A
Bontovics
Erika
E
Chapman
Martin
M
Gravel
Denise
D
Henry
Bonnie
B
Lapinsky
Stephen
S
Loeb
Mark
M
McDonald
L Clifford
LC
Ofner
Marianna
M
Paton
Shirley
S
Reynolds
Donna
D
Scales
Damon
D
Shen
Sandy
S
Simor
Andrew
A
Stewart
Thomas
T
Vearncombe
Mary
M
Zoutman
Dick
D
Green
Karen
K
D000368:Aged; D002170:Canada / Q000453:epidemiology; D003710:Demography; D004196:Disease Outbreaks; D005260:Female; D006282:Health Personnel; D006801:Humans; D017758:Infectious Disease Transmission, Patient-to-Professional / Q000706:statistics & numerical data*; D007440:Intubation; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012044:Regression Analysis; D012307:Risk Factors; D045169:Severe Acute Respiratory Syndrome / Q000453:epidemiology / Q000635:transmission*