Risk Factors for SARS Transmission from Patients Requiring Intubation: A Multicentre Investigation in Toronto, Canada

PLOS ONE, May 2010

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 ≥20 (OR = 17.05, p = .009) and patient Pa02/Fi02 ratio ≤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. Conclusion 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.

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Risk Factors for SARS Transmission from Patients Requiring Intubation: A Multicentre Investigation in Toronto, Canada

Canada. PLoS ONE 5(5): e10717. doi:10.1371/journal.pone.0010717 Risk Factors for SARS Transmission from Patients Requiring Intubation: A Multicentre Investigation in Toronto, Canada Janet Raboud 0 Altynay Shigayeva 0 Allison McGeer 0 Erika Bontovics 0 Martin Chapman 0 Denise 0 Gravel 0 Bonnie Henry 0 Stephen Lapinsky 0 Mark Loeb 0 L. Clifford McDonald 0 Marianna Ofner 0 Shirley Paton 0 Donna Reynolds 0 Damon Scales 0 Sandy Shen 0 Andrew Simor 0 Thomas Stewart 0 Mary Vearncombe 0 Dick Zoutman 0 Karen Green 0 Joel Mark Montgomery, U.S. Naval Medical Research Center Detachment/Centers for Disease Control, United States of America 0 1 Division of Infectious Diseases, University Health Network , Toronto, Ontario , Canada , 2 Dalla Lana School of Public Health, University of Toronto , Toronto, Ontario , Canada , 3 Mount Sinai Hospital , Toronto, Ontario , Canada , 4 Department of Laboratory Medicine and Pathology, University of Toronto , Toronto, Ontario , Canada , 5 Ontario Ministry of Health and Long Term Care , Toronto, Ontario , Canada , 6 Department of Anesthesia, University of Toronto , Toronto, Ontario , Canada , 7 Sunnybrook Health Sciences Centre , Toronto, Ontario , Canada , 8 Public Health Agency of Canada , Ottawa, Ontario , Canada , 9 British Columbia Centre for Disease Control , Vancouver, British Columbia , Canada , 10 Department of Medicine, University of Toronto , Toronto, Ontario , Canada , 11 Department of Pathology and Molecular Medicine, McMaster University , Hamilton, Ontario , Canada , 12 Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America, 13 Durham Region Health Department , Whitby, Ontario , Canada , 14 Department of Microbiology and Immunology, Queen's University , Kingston, Ontario , 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 intervieweradministered 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 $20 (OR = 17.05, p = .009) and patient Pa02/Fi02 ratio #59 (OR = 8.65, p = .001) were associated with increased risk of transmission of SARSCoV. In CART analyses, the four covariates which explained the greatest amount of variation in SARS-CoV transmission were covariates representing individual patients. Conclusion: 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. Funding: This research was funded by a contract from the Ontario Ministry of Health and Long Term Care. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. On March 7, 2003, a son of Canadas index SARS case was admitted to a hospital in Toronto with a diagnosis of communityacquired pneumonia. Because he and other family members were not identified as infected with SARS CoV until March 13, infection was transmitted to patients, volunteers, visitors and health care workers in this community hospital, and subsequently in other hospitals and the community throughout Greater Toronto Area (GTA). Over the next three months, SARS-CoV would be transmitted to 375 persons in Toronto, 271 (72%) of whom acquired their infections in health care settings.[13] The healthcare workers at greatest risk of acquiring SARS were those caring for critically ill SARS patients, and transmission was documented despite the use of recommended personal protective (...truncated)


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Janet Raboud, Altynay Shigayeva, Allison McGeer, Erika Bontovics, Martin Chapman, Denise Gravel, Bonnie Henry, Stephen Lapinsky, Mark Loeb, L. Clifford McDonald, Marianna Ofner, Shirley Paton, Donna Reynolds, Damon Scales, Sandy Shen, Andrew Simor, Thomas Stewart, Mary Vearncombe, Dick Zoutman, Karen Green. Risk Factors for SARS Transmission from Patients Requiring Intubation: A Multicentre Investigation in Toronto, Canada, PLOS ONE, 2010, Volume 5, Issue 5, DOI: 10.1371/journal.pone.0010717