Background Installing physical barriers at suicide hotspots is known as an effective strategy for suicide prevention. However, the effectiveness of physical barriers may be nullified by the substitution phenomenon, i.e., that restricting access to a particular place induces people at risk to look for a nearby place for suicide. Methods This study tests whether the substitution phenomenon exists in the case of railway and metro suicides. We focused on the prevention effort by a Japanese railway company that installed blue light-emitting-diode (LED) lamps on railway platforms to prevent people from diving to a running train. Using panel data of 71 train stations between 2000 and 2013, we compared the number of suicides before and after the installation of the blue lights at 14 stations where the lights were installed and at neighboring five stations on the same railway line, using the number of suicides at all other stations without the intervention as a control group. Findings Our regression analysis shows that the introduction of blue lights decreased the number suicides by 74% (CI: 48-87%) at stations where the blue lights were installed, while it did not result in a systematic increase in the number of suicides at the neighboring stations. Interpretation The installation of blue lights generated no systematic substitution phenomenon at nearby stations.
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