Restricting access to a suicide hotspot does not shift the problem to another location. An experiment of two river bridges in Brisbane, Australia

Abstract

Background: Restricting access to lethal means is a well-established strategy for suicide prevention. However, the hypothesis of subsequent method substitution remains difficult to verify. In the case of jumping from high places ('hotspots'), most studies have been unable to control for a potential shift in suicide locations. This investigation aims to evaluate the short and long-term effect of safety barriers on Brisbane's Gateway Bridge and to examine whether there was substitution of suicide location. Methods: Data on suicide by jumping - between 1990 and 2012, in Brisbane, Australia - were obtained from the Queensland Suicide Register. The effects of barrier installation at the Gateway Bridge were assessed through a natural experiment setting. Descriptive and Poisson regression analyses were used. Results: Of the 277 suicides by jumping in Brisbane that were identified, almost half (n=126) occurred from the Gateway or Story Bridges. After the installation of barriers on the Gateway Bridge, in 1993, the number of suicides from this site dropped 53.0% in the period 1994-1997 (p=0.041) and a further reduction was found in subsequent years. Analyses confirmed that there was no evidence of displacement to a neighbouring suicide hotspot (Story Bridge) or other locations. Conclusions: The safety barriers were effective in preventing suicide from the Gateway Bridge, and no evidence of substitution of location was found.