Cumulative evidence of helmet effects on bicycle injuries

Abstract

Background: With widely-used use of bicycles, studies of helmet effects on bicycle injuries were intensively conducted after the problem of bicycle injuries emerged. This study aims to justify whether current evidence is sufficient to manifest the effects of helmets. Methods：We exhaustively searched the articles in the databases of Medline, Scopus, and Embase by the term of (helmet* AND (cycl* OR bicycle* OR bike*)) AND injur* by the time of April 10, 2019. The meta-analysis and SSA (study sequential analysis) were conducted. Results：A total of 55 studies are eligible for meta-analysis. The OR (odds ratio) of helmet effect on head injuries compared with other injuries is 0·50 (0·43, 0·59) and effect of helmets on serious head injuries compared with other injuries are protective with OR of 0·34 (0·28, 0·43). Compared with control injuries, the OR of helmet effect on facial injuries is 0·63 (0·45, 0·88). Helmets is not associated with protective effects of neck injuries and OR is 0·98 (0·82, 1·17). SSA results of head injuries, serious head injuries, and face injuries showed, the cumulative Z-curve crossed both the conventional and the trial sequential monitoring boundary. SSA results of neck injuries showed the cumulative Z-curve does not cross both the conventional and the trial sequential monitoring boundary. Conclusions：The helmet has protection effects on head injuries, serious head injuries, and face injuries. The SSA showed the current evidence was sufficient to support the results. More studies of helmet promotion are warranted in the future. Key words: helmet; bicycle injuries; head injuries; face injuriesKey words: helmet; bicycle injuries; head injuries; face injuries