Use of conspicuity aids by cyclists and risk of crashes involving other road users: Population based case-control study

•There is conflicting evidence as to whether use of conspicuity aids is associated with a reduced risk of a crash in cyclists.•This matched case-control study included cases attending an emergency department following a cycling collision crash.•There was no evidence of a reduced risk of a crash associated with use of conspicuity aids and some evidence of an increased risk, but this may reflect biases and residual confounding.•Further research is needed to evaluate bicycle crash prevention measures.