Effect of a barrier at Bloor Street Viaduct on suicide rates in Toronto: natural experimentBMJ 2010; 341 doi: https://doi.org/10.1136/bmj.c2884 (Published 06 July 2010) Cite this as: BMJ 2010;341:c2884
- 1Department of Psychiatry, University of Toronto, ON, Canada
- 2Department of Psychiatry, Sunnybrook Health Sciences Centre and Women’s College Hospital. 2075 Bayview Avenue, Toronto, ON, Canada M4N 3M5
- Correspondence to: M Sinyor
- Accepted 27 April 2010
Objective To determine whether rates of suicide changed in Toronto after a barrier was erected at Bloor Street Viaduct, the bridge with the world’s second highest annual rate of suicide by jumping after Golden Gate Bridge in San Francisco.
Design Natural experiment.
Setting City of Toronto and province of Ontario, Canada; records at the chief coroner’s office of Ontario 1993-2001 (nine years before the barrier) and July 2003-June 2007 (four years after the barrier).
Participants 14 789 people who completed suicide in the city of Toronto and in Ontario.
Main outcome measure Changes in yearly rates of suicide by jumping at Bloor Street Viaduct, other bridges, and buildings, and by other means.
Results Yearly rates of suicide by jumping in Toronto remained unchanged between the periods before and after the construction of a barrier at Bloor Street Viaduct (56.4 v 56.6, P=0.95). A mean of 9.3 suicides occurred annually at Bloor Street Viaduct before the barrier and none after the barrier (P<0.01). Yearly rates of suicide by jumping from other bridges and buildings were higher in the period after the barrier although only significant for other bridges (other bridges: 8.7 v 14.2, P=0.01; buildings: 38.5 v 42.7, P=0.32).
Conclusions Although the barrier prevented suicides at Bloor Street Viaduct, the rate of suicide by jumping in Toronto remained unchanged. This lack of change might have been due to a reciprocal increase in suicides from other bridges and buildings. This finding suggests that Bloor Street Viaduct may not have been a uniquely attractive location for suicide and that barriers on bridges may not alter absolute rates of suicide by jumping when comparable bridges are nearby.
We thank James Edwards (regional supervising coroner for Toronto East) and the entire staff at the Office of the Chief Coroner of Ontario, including Dorothy Zwolakowski, June Lindsell, Tina Baker, and Karen Bridgman-Acker, for making this research possible; Ian Johnson and the determinants of community health course at the University of Toronto medical school for facilitating the genesis of this project; Alex Kiss (Department of Research Design and Biostatistics, Sunnybrook Health Sciences Centre) for performing some of the statistical analyses; and Donald Redelmeier (director of the Clinical Epidemiology Unit, Sunnybrook Health Sciences Centre) and David Streiner (senior scientist, Kunin-Lunenfeld Applied Research Unit, Baycrest) for their advice and counsel.
Contributors: MS developed the idea for this study, contributed to the study design, analysed the data, interpreted the results, and drafted the manuscript. He is guarantor. AJL contributed to the study design, interpreted the results, and critically revised the manuscript. Both authors had full access to all of the data (including statistical reports and tables) in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis.
Funding: This study received no funding.
Competing interests: All authors have completed the unified competing interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare (1) no financial support for the submitted work from anyone other than their employer; (2) AJL has acted as a consultant for Janssen Ortho, Biovail, and Eli Lilly Canada; (3) no spouses, partners, or children with relationships with commercial entities that might have an interest in the submitted work; and (4) no non-financial interests that may be relevant to the submitted work.
Ethical approval: This study was approved by the University of Toronto’s research ethics board.
Data sharing: No additional data available.
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