Geen helm blijkt ... veiliger.
En waaruit blijkt dat ? Frankrijk versus UK alleszins zeker niet.
Toch beter zo wetenschappelijk mogelijk onderzoek nemen, een discussie over alle studies:
http://www.sciencedirect.com/science/article/pii/S0001457512004253
Abstract
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This paper presents a re-analysis of the study. The re-analysis included: (1) Ensuring the inclusion of all published studies by means of continuity corrections of estimates of effect relying on zero counts; (2) detecting and adjusting for publication bias by means of the trim-and-fill method; (3) detecting and trying to account for a time-trend bias in estimates of the effects of bicycle helmets; (4) updating the study by including recently published studies evaluating the effects of bicycle helmets. The re-analysis shows smaller safety benefits associated with the use of bicycle helmets than the original study.
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4. Updating the meta-analysis
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Table 4 shows summary estimates of effect based on the original estimates, the new estimates and all estimates. Estimates based on recently published studies show much smaller effects of bicycle helmets on head injury and facial injury than the original study. In fact, in the random-effects model, there is a statistically non-significant tendency for the wearing of bicycle helmets to be associated with an increase of the risk of facial injury. As far as neck injury is concerned, the tendency found in the original study for the risk of injury to increase when a helmet is worn is confirmed when a new estimate is added.The head, the face and the neck can be viewed as three distinct regions of the body. Hence, it makes sense to develop summary estimates of effect of bicycle helmets for the head, the face and the neck. These estimates are shown at the bottom of Table 4. In general, the estimates suggest a moderate overall effect of bicycle helmets. In the random-effects analysis, based on the new estimates only, the effect is not statistically significant at the 5% level. For all studies, based on a random-effects model adjusted for publication bias, the best estimate is a 33% reduction of the risk of injury to the head, the face or the neck if a bicycle helmet is worn. This summary estimate is statistically significant at the 5% level.
Table 4.
Summary estimates of effects of bicycle helmets. New studies added.
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5. Discussion
Do bicycle helmets reduce the risk of injury to the head, face or neck? With respect to head injury, the answer is clearly yes, and the re-analysis of the meta-analysis reported by Attewell et al. (2001) in this paper has not changed this answer. As far as facial injury is concerned, evidence suggests that the protective effect is smaller, but on balance there does seem to be a slight protective effect. The risk of neck injury does not seem to be reduced by bicycle helmets. There are only four estimates of effect, but they all indicate an increased risk of injury. When the risk of injury to head, face or neck is viewed as a whole, bicycle helmets do provide a protective effect. This effect is statistically significant in older studies. New studies, summarised by a random-effects model of analysis, indicate only a statistically non-significant protective effect.
These findings raise a number of issues. In the first place, why do recent studies show a smaller protective effect of bicycle helmets than older studies? In the second place, should a meta-analysis include all studies or just studies that satisfy certain selection criteria, like those applied in the Cochrane review of bicycle helmets (Thompson et al., 2009)? In the third place, why are the findings of some studies that have evaluated the effects of laws mandating the use of bicycle helmets apparently inconsistent with the findings of studies of the protective effect of bicycle helmets for each user?
There are two main reasons why the findings of studies that have evaluated the effects of bicycle helmets can vary: substantive and methodological. One reason for varying findings is that different types of helmets do not have the same protective effect. The first studies of bicycle helmets included mostly hard shell helmets. These have been found to offer better protection against head injury than soft shell helmets, which have become more popular over time. Thus, in the study of Hansen et al. (2003) more than one third of the helmets were soft shell helmets and these helmets were found to protect less well against head injury than hard shell helmets. Thompson et al. (2009) dismiss this argument, claiming that (page 7): “Bicycle helmets of all types … provide substantial protection for cyclists of all ages.” However, the same authors (Rivara et al., 1997) reported a study which found that only hard shell helmets protected against neck injury; use of a soft shell helmet was associated with an increased incidence of neck injury. On balance, the evidence suggests that: (1) Soft shell helmets offer less protection than hard shell helmets and (2) soft shell helmets appear to have become more common over time.
Thompson et al. (2009) were concerned about the quality of studies that have evaluated the effects of bicycle helmets and defined a set of selection criteria for including studies in a meta-analysis. Applying these criteria, seven studies were included and eight studies were omitted. Two studies were awaiting assessment at the time of publication of the review. Four of the seven studies that were included were performed by the same researchers as the Cochrane review. In short, Thompson et al. classified four of their own studies as good enough to be included in the meta-analysis, but excluded eight studies, none of which they were involved in. Littell et al. (2008) regard involvement in the conduct of one or more studies included in a review, or publication of a previous review on the same topic as a case of conflict of interest. This conflict of interest is relevant for the Cochrane review reported by Thompson et al. (2009). They were themselves authors of four of the seven studies included and had performed a similar Cochrane review twice before (in 2003 and 2006). To their credit, however, Thompson et al. included a very comprehensive section discussing criticisms of their review.
Study quality assessment is not an exact science. The Department for Transport in Great Britain issued a report in 2002 entitled: “Bicycle helmets – a review of their effectiveness: A critical review if the literature.” The report includes an assessment of the quality of 16 studies that have evaluated the effects of bicycle helmets. Studies were rated as good, reasonable or weak. Of the seven studies Thompson et al. (2009) included in the Cochrane review, one was rated as good, two as good/reasonable, three as reasonable and one as reasonable/weak. Three of the eight studies Thompson et al. omitted were also rated by the Department for Transport (2002). One was rated as good, one as good/reasonable and one as reasonable. Thus, if the rating developed by the Department for Transport is applied, it is by no means obvious that all the seven studies that were included by Thomson et al. ought to have been included. Nor is it clear that all the omitted studies were of lower quality than the studies included.
An alternative to omitting studies classified as bad would be to develop a quality score for each study and use that score in a sensitivity analysis, as illustrated by Elvik (2005). Although it is clear that any numerical quality score will contain an element of arbitrariness, including all studies and performing a sensitivity analysis allows readers to judge how study quality influences study findings. This opportunity does not exist if studies rated as “bad” are simply omitted.
Several researchers have been puzzled by the fact that, on the one hand, studies have reported large protective effects of bicycle helmets; on the other hand, studies of the effect of legislation that has been associated with large increases in the rate of helmet wearing have not always shown a clear decline in the number of head injuries among cyclists. There are at least two reasons why even a large increase in the rate of helmet wearing will not necessarily lead to a major reduction of the number of cyclists sustaining head injury. One reason could be selective recruitment, which means that it is the most cautious and safety-minded cyclists, with a lower rate of accident involvement than other cyclists, who first start wearing helmets. If, for example, in a population of cyclists 60% have a 20% lower rate of accident involvement than an average cyclist (i.e. a relative risk of 0.8 ), and these cyclists start wearing helmets that reduce their risk of head injury by 40%, the total number of head injuries would be reduced by 19% (0.8 × 0.60 = 0.48; i.e. the safe cyclists are involved in 48% of all accidents before starting to wear helmets; this reduces by 0.8 × 0.6 × 0.40 = 0.19; ceteris paribus the number of injuries is reduced by 19%). This is less than one would expect if aggregate effects were strictly proportional to individual effects. In the latter case, one would expect the number of head injuries to be reduced by 0.40 × 0.60 = 0.24 = 24%. If there is very selective recruitment, aggregate effects could be substantially smaller than implied by the individual protective effects of bicycle helmets.
Another possible reason why the aggregate effects of bicycle helmets could be smaller than expected on the basis of individual effects is behavioural adaptation. Once helmeted, cyclists might feel better protected and adopt more risky riding behaviour. While this cannot be ruled out, there is no direct evidence for it and performing a convincing study of such behavioural adaptation would be very difficult. The issue remains unresolved (Robinson, 2007).
6. Conclusions
Based on the studies reviewed in this paper, the following conclusions can be drawn:
1.
A re-analysis has been performed of a meta-analysis of the protective effects of bicycle helmets reported in Accident Analysis and Prevention (Attewell et al., 2001). The original analysis was found to be influenced by publication bias and time-trend bias that were not controlled for. When these sources of bias are controlled for, the protective effects attributed to bicycle helmets become smaller than originally estimated.
2.
When the analysis is updated by adding four new studies, the protective effects attributed to bicycle helmets are further reduced. According to the new studies, no statistically significant overall effect of bicycle helmets could be found when injuries to head, face or neck are considered as a whole.
3.
The findings of this study are inconsistent with other meta-analyses, in particular a Cochrane review published in 2009. However, the study inclusion criteria applied in the Cochrane review are debatable.
via Wiki gevonden:
ook via D-Wiki:
http://de.wikipedia.org/wiki/Fahrradhelm#NutzenZweden heeft toch redelijk overtuigende cijfers:
Schweden
In Schweden besteht seit dem 1. Juli 2005 eine Helmpflicht für Radfahrer unter 15 Jahren. Der Anteil Helm tragender Kinder unter 10 Jahren in Wohngebieten ist zwischen 2005 und 2012 von 35% auf 70% gestiegen, im selben Zeitraum stieg die Helmtragequote für Kinder zwischen 6 bis 15 Jahren, die zur Schule fahren, von 37 % auf 59%. Die Gesamtzahl schwer verletzter Radfahrer (Krankenhausaufenthalt) blieb für dieselbe Periode etwa gleich (~3.000 p.a.), die Zahl getöteter Radfahrer ist von 35 auf 23 gesunken. Für Erwachsene blieb die Helmtragequote zwischen 2007 und 2012 stabil auf 27%, in diesem Zeitraum nahm die Gesamtzahl der getöteten Radfahrer von 33 auf 23 ab[47] (Vergleich zu 1998 bei 18% Helmtragequote: 58[48]). Die schwedische Firma Hövding hat 2010 einen „unsichtbaren“ Fahrradhelm auf den Markt gebracht, der wie ein Airbag funktioniert.[49] Dieser soll das Tragen eines Fahrradhelms auch für Erwachsene attraktiver machen.
evolutie bij evenveel gekwetste fietsers (ziekenhuis) wel significant minder dode fietsers, hoofdkwetsuren spelen bij dodelijkheid een grote rol. Al komt het maar volgens bepaalde studies in 5 à 10 % van alle fietsongevalkwetsuren tot een "hoofd-kwetsuur"
Das britische Verkehrsministerium kam nach Auswertung von 16 Studien zu dem Schluss, dass alle Studien eine Schutzwirkung nachweisen, die Aussagen über das Ausmaß der Schutzwirkung jedoch variieren.[4] Diverse Studien, deren Ergebnisse nicht unwidersprochen geblieben sind, behaupten, dass das Tragen von Fahrradhelmen die Kopfverletzungen um bis zu 88 Prozent reduziere und auch die Todesrate bei Fahrradunfällen senke.[5][6][7] Insofern wird gefolgert, dass Fahrradhelme einen wirksamen und sinnvollen Schutz darstellten.[8] Folglich sei auch die Helmbenutzung eine sinnvolle und wichtige Maßnahme zur Verringerung von Kopfverletzungen.
Andere Untersuchungen kamen zu einem Anteil der Kopfverletzungen an allen Verletzungen von Fahrradfahrern von nur etwa 5 bis 10 %.
Een helm dragen is natuurlijk
enkel een passieve beschermmaatregel...
Aja de Belgische registratie bij fietsersongevallen zonder motorvoertuigbetrokkenheid zal wel verschrikkelijk ondermaats zijn... Be heeft daar nog altijd van die rare wetten... waardoor ziekenhuizen niet verplicht zijn (medisch geheim enz...)
http://www.seniorennet.be/Magazine/artikel/61/onthutsende-cijfers-verkeersslachtoffers-vooral-fietsers-de-dupe
De politie telde “maar” 903 zwaargewonde fietsers. De ziekenhuizen hielden het op 4.906 zwaargewonde fietsers ofwel 5 keer zoveel als de politie.
