Reply to the letter: “Unreliable claims regarding bicycle helmet law in Western Australia”

Abstract

We would like to thank Clarke et al. for their interest in our study and the topic of helmets’ efficacy in preventing traumatic brain injury. The authors of the response letter mainly criticise the following statement made in the conclusion “Our findings provide a strong incentive for other countries to consider introducing and enforcing compulsory helmet laws”. They claim that this conclusion ignores several of our own findings. If we only considered the results of the current study, the conclusion could maybe be worded more cautiously. However, taking all available scientific literature into consideration, we think that in accordance with the main results and the available peer reviewed literature the conclusion is justified. The limitations of our study are discussed in our article. The conclusion that the compulsory helmet law in Western Australia (WA) is effective in TBI prevention is based on a percentage comparison of bicycle related hospital admission with TBI. Admissions with moderate to severe TBI (1%) in our Western Australian study is much lower than in other studies looking at similar populations in countries without a helmet legislation [1, 3, 7, 10]. Table 3 of our publication shows cyclist related admissions with no TBI were significantly (p < 0.01) more often wearing helmets (80%), compared to admissions with TBI (66%) [4]. Clark et al. wrote that “WA helmet wearing surveys haven’t been conducted since the 1990s” but “that media reports and anecdotal evidence suggest about 40% of cyclists ride without one.” The claim of about 40% of cyclists riding without a helmet is not supported by the two articles cited in their letter and is most likely caused by a misinterpretation of data presented in the WA State Trauma Registry report that present percentages of bicycle related admissions including those with unknown helmet status [9, 13]. Furthermore, both articles mention basically the same source. One mentions that 19.4% of bicycle crash related admissions to Royal Perth Hospital were not wearing helmets and the other is a newspaper article in which the interviewee, the head of the Western Australian State Trauma Unit Royal Perth Hospital (RPH), mentions “about 20 percent of cyclists admitted to RPH had not been wearing a helmet” [13]. These helmet use rates in Western Australia basically mirror our data sourcing from the “Western Australian State Trauma Registry”. Clark et al. write that “Evidence from WA suggests the overall population’s helmet wearing percentage is lower than the percentage who suffer TBI and, indeed, all forms of hospitalised injury”. Is there any reference/source to that claim? As mentioned, the only real-time observational data of compliance with a compulsory helmet law is in a study from Queensland, Australia, which demonstrated more than 98.3% compliance [8]. Therefore, we doubt that there are much more bicyclists that do not wear helmets in Western Australia. We would also like to correct the claim that our “study fails to adequately consider why helmeted cyclists had more severe TBI”. We would like to highlight that there was no statistically significant difference in severity categories found between helmeted and unhelmeted bicycle related admissions. It is true that in our study there were more severe (GCS 3–8) TBI patients in the helmeted group. There were also more patients with moderate (GCS 9–12) TBI in the unhelmeted group than in the helmeted This article is part of the Topical Collection on Brain trauma