3.4 DISCUSSION3.4 DISCUSSION
3.4 DISCUSSION
Cycling is a popular form of transport and recreation in the Netherlands. Although cycling improves fitness and health, it is not without risks. The purpose of this paper was to assess the incidence and costs of bicycle-related traumatic brain injury across various age groups, and compared them with data on all bicycle-related injuries treated at Dutch EDs between 1998 and 2012. We conclude that incidence
0 5,000 10,000 15,000 20,000 25,000 0-14 15-24 25-44 45-64 65+ C o st s p e r ca se ( E u ro ) Age (years) Indirect costs Direct costs 0 5,000 10,000 15,000 20,000 25,000 0-14 15-24 25-44 45-64 65+ C o st s p e r ca se ( E u ro ) Age (years) Indirect costs Direct costs
46 46 46
46 | Epidemiology of traumatic brain injury
of ED treatments due to cycling are high (456/100,000 persons) and often involve TBI (9%; 43/100,000). Between 1998 and 2012, the incidence of ED treatments due to bicycle-related TBI strongly increased, while this incidence due to all bicycle-related injuries remained stable. The incidence of hospital admissions, however, increased in both TBI and all injuries from cycling. In the same period, the injury rate of TBI per kilometres travelled increased in all age groups (44%) except children (–12%), whereas the overall injury rate of all injuries decreased (–4%) especially in children (–36%). Although bicycle- related TBI accounted for 9% of the incidence of all ED treatments due to cycling, it accounted for 18% (€74.5 million) of the total costs due to all bicycle-related injuries (€410.7 million). Both direct and indirect costs per patient were far higher for cyclists diagnosed with TBI than all injuries from cycling, as TBI patients had more severe injuries, were more often admitted to a hospital or intensive care, and were longer absent from work. Our study identified children and adolescents aged 0–24 to have the highest incidence of ED treatments due to bicycle-related injuries. Although incidence of all bicycle- related injuries and TBI was relatively low in cyclists aged 25–54, men in the working population (age 15–64) had highest indirect costs due to their loss of productivity. Older cyclists aged 55+ were identified as main risk group for TBI, as they represented highest ED attendance, injury severity, admission to hospital or intensive care unit, and economic costs.
The strength of our study lies in the detailed data on demographics, injury mechanism, injury severity (MAIS) and costs of bicycle-related injuries treated at Dutch EDs. Our study therefore provides population-based weighted estimates of the incidence and costs of injuries among all types of cyclists (sports and non-sports) in the Netherlands. In addition, our data provides insight into the trends of ED treatments and hospital admissions due to injuries from cycling over a period of 15 years. In contrast to cost estimations in previous studies, our cost-of-illness assessment included both direct and indirect costs, which were calculated with use of information on real health care volumes, work absence and return to work obtained from patient follow-up surveys.
Incidence and trends Incidence and trends Incidence and trends Incidence and trends
Our estimated incidence of 456 ED treatments per 100,000 persons due to injuries from cycling was much higher than previously reported population-based incidence of ED treatments elsewhere in the world; <1/100,000 persons in Tanzania35 and Sweden,8 10 in Iran,36 50 in Canada,37 80 in France,6 and
163 in the United States.38 This higher Dutch incidence is most likely caused by the more frequent use
of bicycles and therefore higher risk of bicycle-related injuries in the Netherlands than in other countries: in the Netherlands one third of all journeys are made by bike.33 In contrast, in other European
countries approximately 2–20% of all journeys are made by bike.2 In car-oriented countries such as
Canada and the United States, only 1% of daily trips are made by bike.39
The finding that bicycle-related TBI accounted for 9% of all bicycle-related injuries, is lower than the proportion of head injuries reported in other studies, namely 22–35% in the USA, Sweden, and Finland.5,10,11 This difference in proportion is likely explained by the disparity in TBI definition. Whereas
this study only included patients diagnosed with traumatic brain injury, other studies included all head injuries (including facial fractures, and open wounds or superficial injuries to the head). In addition, the difference in proportion of head injuries may be explained by differences in cycling populations, as in the abovementioned Northern European countries cycling levels remain high, even among the elderly.40
Chapter 3 | 47474747
Our study showed a strong increase in the incidence of ED treatments due to bicycle-related TBI between 1998 and 2012. In this period, the number of hospital admissions due to bicycle-related TBI and all injuries from cycling increased in all age groups in the Netherlands. Such findings have also been reported for adolescents (aged 13–17) and adults (aged 18+) without head injuries in Alberta, Canada.41
The increase in hospital admissions in the Netherlands is likely explained by an increase in injury severity of patients visiting an ED, as the number of patients with multiple injuries and the number of patients admitted to the intensive care increased over time. In addition, estimates of the Global Burden of Diseases, Injuries, and Risk Factors Study 2010 (GBD 2010) showed a constant increase in the number of years lived with disability (YLDs – the non-fatal component of disability adjusted life-years (DALYs)) from pedal cycling in Western Europe, approximately 30% from 1990 to 2010.42
Patient characteristics and outcome
Patient characteristics and outcomePatient characteristics and outcome
Patient characteristics and outcome
Our finding that in all age groups the majority of bicycle-related TBI and all bicycle-related injuries were caused by a fall or collision with a motor vehicle is in line with results of other studies.6-10,43
Our study indicated that the incidence of ED treatments due to bicycle-related TBI are highest in adults aged 55+, which is in line with previous studies that reported that older cyclists tended to have a higher risk of (serious) injuries from cycling than the younger age groups.7,8,11,13 This confirms our finding that
bicycle-related TBI imposed far more severe injuries (98% MAIS 2+) than all bicycle-related injuries. In our sample, the majority (76%) of all bicycle-related injuries involved minor or moderate injuries (MAIS 1-2), which is in line with other findings in injured cyclists.5,12 The difference in injury severity between
TBI and all injuries from cycling may explain the fact that we found far higher hospital admission rates in cyclists diagnosed with TBI (64%) than in all injured cyclists (19%).
Direct and indirect costs
Direct and indirect costsDirect and indirect costs
Direct and indirect costs
Total direct and indirect costs of bicycle-related injuries treated at EDs were €10,130 per patient, which was higher than estimates in other European countries: €3,180 in Finland5 and €4,290 in Sweden11 after
adjustment for inflation up to 2012. Although the Finnish study estimated the same costs and included both costs of treatment and labour absenteeism, the Swedish study estimated only the costs of out- and inpatient care in older adults (65+ years). However, a study in Norway estimated costs of health care and lost output per cyclist injured or killed, similar to estimates in our study: ranging from €1,470 for minor injuries (AIS1) to €19,610 for moderate injuries (AIS2)12 after adjustment for inflation up to
2012.
In addition to previous studies, we found the total costs of survivors of bicycle-related TBI to be even higher (on average €19,620 per patient), because these TBI patients were more often warranted to the hospital and intensive care, and were longer absent from work (on average 46 days). Our estimates were higher than those of head injured cyclists used for cost-effectiveness of bicycle helmet campaigns or laws, estimating acute medical treatment costs as being €64 per patient,22 and direct medical costs
of hospitalisation as being €1,310 in children aged 5–12, €1,350 in adolescents aged 13–18, and €1,130 in adults aged 18+.23
According to our study, in both bicycle-related TBI and all injuries from cycling, the mean indirect costs per case were up to three times higher than the mean direct costs per case, and higher in men than in women (on average 3–5 more omitted workdays). Previous research on minor bicycle accidents in
48 48 48
48 | Epidemiology of traumatic brain injury
Belgium, also indicated productivity loss to be the most important component of total cost due to cycling injuries.44 The difference in omitted workdays and indirect costs between men and women can
be explained by the fact that in the Netherlands many women, especially mothers, work part-time: 75% of women aged 25 to 54 with dependent children work part-time, compared to only 26% in France.45 Limitations
Limitations Limitations Limitations
The epidemiology and costs of bicycle-related TBI and all bicycle-related injuries reported in this study are conservative since they represent only injury patients who were treated at the ED and/or hospitalised. Estimates of the Dutch Consumer and Safety Institute indicate that for every injured cyclist treated at the ED, 1 to 2 consulted a general practitioner, and 2 did not seek medical care.4 Hence, the
actual incidence and cost-of-illness due to bicycle-related TBI and all bicycle-related injuries may be even higher. It should also be noted that this study could not provide complete information on mortality among injured cyclists, because national death statistics are only available for specific diseases or specific injury mechanisms. However, information on the injury severity (MAIS) showed that 482 (4%) of all cyclists died (MAIS 6) in the hospital because of their injuries. The majority of these patients (n=452, 94%) was diagnosed with TBI. According to the MAIS, total in-hospital mortality rate in bicycle- related TBI was 14%. Overall mortality rates are expected to be even higher, because the MAIS only provides information on the in-hospital mortality.
The incidence of bicycle-related TBI and all injuries from cycling were not kilometre-adjusted. However, we did include information on cycle use and the injury rate of both bicycle-related TBI and all injuries from cycling per kilometre travelled. This data showed that between 1998 and 2012, cycle use increased in the Netherlands. In the same period, the injury rate of bicycle-related TBI increased (except in children), whereas the overall injury rate of all bicycle-related injuries decreased.
A final limitation of our study is that since helmet use is not registered in the LIS database, the effects of helmet use could not be studied.
Implications for prevention Implications for prevention Implications for prevention Implications for prevention
This study showed older cyclists (aged 55+ years) to have a higher risk of (serious) injuries from cycling than younger cyclists, both with respect to incidence and injury rate, and identified them as an important risk group for TBI. However, so far, prevention strategies in the Netherlands have been mainly focussing on children and the use of bicycle-helmets in these young and vulnerable cyclists. This has led to an increase in the purchase and/or use of bicycle helmets in children.46-48 Efforts to increase helmet
use may have been effective, as our study showed a 30% decrease in ED treatments due to all bicycle- related injuries and a 12% decrease in the injury rate of TBI per kilometre travelled in 0–14-year olds between 1998 and 2012, and a 6% decrease in ED treatments due to bicycle-related TBI in girls aged 0– 14. Also, preliminary results of a campaign in the southern part of the Netherlands, in which free bicycle helmets are provided to all children in primary schools, indicate that after the implementation of this campaign the number of young cyclists with TBI decreased.46 The latter provides further support for the
effectiveness of community based helmet promotion programmes.
Bicycle helmets may also be of use among older cyclists. In the Netherlands, nowadays, helmet use is not mandatory and is unusual among most cyclists. Bicycle helmets are only used during sports among road cyclists and mountain bikers, and by young children. However, it has been shown in other countries
Chapter 3 | 49494949
that bicycle helmets reduce the incidence, proportion and severity of head injuries among helmet users.5,9,36,49,50
Finally, as older cyclists showed higher injury rates of TBI per kilometre travelled compared to other age groups, and increased cycling is expected to increase TBI in the older age groups, prevention strategies should target on education and training for the physical vulnerable elderly in traffic, especially those using electrical bicycles. Our finding that both the number of ED treatments due to injuries from cycling and injury rate per kilometre travelled increased in adults aged 55+, may be caused by the increasing popularity of electrically assisted bicycles1,51,52 in this age group.53 In 2011, 13% of all ED treatments due
to bicycle-related injuries in the Netherlands involved users of an electrical bicycle, often aged 60+ (72%).54 Although injury characteristics seemed similar, in contrast to users of classical bikes, elderly
users of electrical bikes were more often injured due to a fall (18% versus 12%). A possible explanation could be the weight of the electrical bicycle, which the elderly indicated to be too high.54 Also, results
of a recent study on the road safety implications of the use of electric bicycles in the Netherlands suggest that users of electric bicycles are more at risk of having a crash that requires treatment at an ED than users of classical bicycles.55 Further research is needed to minimise the risk and maximise the
health benefits for users of electric bicycles. Overall, education and training for the elderly, and improvements in the cycle infrastructure, may reduce the injury severity, ED attendance, and hospitalisation of elderly cyclists.
Conclusion
ConclusionConclusion
Conclusionssss
This study examined the incidence and costs of bicycle-related TBI and compared them with data on all bicycle-related injuries treated at Dutch EDs between 1998 and 2012. We found that incidence of ED treatments due to cycling are high and often involve TBI, imposing a high burden on individuals and society. Older cyclists aged 55+ were identified as main risk group for TBI to be targeted in preventive strategies, due to their high risk for (serious) injuries and ever-increasing share of ED visits and hospital admissions.
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