Effect of a barrier at Bloor Street Viaduct on suicide rates in Toronto: natural experiment.

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.