[show abstract][hide abstract] ABSTRACT: It is known that experience of a previous crash is related to incidence of future crashes in a cohort of New Zealand cyclists. This paper investigated if the strength of such association differed by crash involvement propensity and by the need for medical care in the previous crash.
The Taupo Bicycle Study involved 2590 adult cyclists recruited in 2006 and followed over a median period of 4.6 years through linkage to four national databases. The crash involvement propensity was estimated using propensity scores based on the participants' demographic, cycling and residential characteristics. Cox regression modelling for repeated events was performed with multivariate and propensity score adjustments. Analyses were then stratified by quintiles of the propensity score.
A total of 801 (31.0%) participants reported having experienced at least one bicycle crash in the twelve months prior to the baseline survey. They had a higher risk of experiencing crash events during follow-up (hazard ratio (HR): 1.43; 95% CI: 1.28, 1.60) but in the stratified analysis, this association was significant only in the highest two quintiles of the propensity score where the likelihood of having experienced a crash was more than 33%. The association was stronger for previous crashes that had received medical care (HR 1.63; 95% CI: 1.41, 1.88) compared to those that had not (HR 1.30; 95% CI: 1.14, 1.49).
Previous crash experience increased the risk of future crash involvement in high-risk cyclists and the association was stronger for previous crashes attended medically. What distinguishes the high risk group warrants closer investigation, and the findings indicate also that health service providers could play an important role in prevention of bicycle crash injuries.
PLoS ONE 01/2014; 9(1):e87633. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Loss to follow-up, if related to exposures, confounders and outcomes of interest, may bias association estimates. We estimated the magnitude and direction of such bias in a prospective cohort study of crash injury among cyclists.
The Taupo Bicycle Study involved 2590 adult cyclists recruited from New Zealand's largest cycling event in 2006 and followed over a median period of 4.6 years through linkage to four administrative databases. We resurveyed the participants in 2009 and excluded three participants who died prior to the resurvey. We compared baseline characteristics and crash outcomes of the baseline (2006) and follow-up (those who responded in 2009) cohorts by ratios of relative frequencies and estimated potential bias from loss to follow-up on seven exposure-outcome associations of interest by ratios of HRs.
Of the 2587 cyclists in the baseline cohort, 1526 (60%) responded to the follow-up survey. The responders were older, more educated and more socioeconomically advantaged. They were more experienced cyclists who often rode in a bunch, off-road or in the dark, but were less likely to engage in other risky cycling behaviours. Additionally, they experienced bicycle crashes more frequently during follow-up. The selection bias ranged between -10% and +9% for selected associations.
Loss to follow-up was differential by demographic, cycling and behavioural risk characteristics as well as crash outcomes, but did not substantially bias association estimates of primary research interest.
[show abstract][hide abstract] ABSTRACT: Regular cycling plays an important role in increasing physical activity levels but raises safety concerns for many people. While cyclists bear a higher risk of injury than most other types of road users, the risk differs geographically. Auckland, New Zealand's largest urban region, has a higher injury risk than the rest of the country. This paper identified underlying factors at individual, neighbourhood and environmental levels and assessed their relative contribution to this risk differential.
The Taupo Bicycle Study involved 2590 adult cyclists recruited in 2006 and followed over a median period of 4.6 years through linkage to four national databases. The Auckland participants were compared with others in terms of baseline characteristics, crash outcomes and perceptions about environmental determinants of cycling. Cox regression modelling for repeated events was performed with multivariate adjustments.
Of the 2554 participants whose addresses could be mapped, 919 (36%) resided in Auckland. The Auckland participants were less likely to be Maori but more likely to be socioeconomically advantaged and reside in an urban area. They were less likely to cycle for commuting and off-road but more likely to cycle in the dark and in a bunch, use a road bike and use lights in the dark. They had a higher risk of on-road crashes (hazard ratio: 1.47; 95% CI: 1.22, 1.76), of which 53% (95% CI: 20%, 72%) was explained by baseline differences, particularly related to cycling off-road, in the dark and in a bunch and residing in urban areas. They were more concerned about traffic volume, speed and drivers' behaviour.
The excess crash risk in Auckland was explained by cycling patterns, urban residence and factors associated with the region's car-dominated transport environment.
Environmental Health 12/2013; 12(1):106. · 2.71 Impact Factor
[show abstract][hide abstract] ABSTRACT: OBJECTIVE: To estimate the incidence and risk of medically or police attended bicycle crashes in a prospective cohort study in New Zealand. METHOD: The Taupo Bicycle Study involved 2590 adult cyclists recruited from the country's largest cycling event in 2006 and followed over a median period of 4.6years through linkage to four administrative databases. Incidence rates with Poisson distribution confidence intervals were computed and Cox regression modelling for repeated events was performed. RESULTS: The 66 on-road crashes and 10 collisions per 1000 person-years corresponded to 240 crashes and 38 collisions per million hours spent road cycling. The risk increased by 6% and 8% respectively for an extra cycling hour each week. There were 50 off-road crashes per 1000 person-years. Residing in urban areas and in Auckland (region with the lowest level of cycling), riding in a bunch, using a road bike and experiencing a previous crash predicted a higher risk. Habitual use of conspicuity aids appeared to lower the risk. CONCLUSION: The risk is higher in urban areas and where cycling is less common, and increased by bunch riding and previous crashes. These findings alongside the possible protective effect of conspicuity aids suggest promising approaches to improving cycle safety.
[show abstract][hide abstract] ABSTRACT: BACKGROUND: Bicycling, despite its health and other benefits, raises safety concerns for many people. However, reliable information on bicycle crash injury is scarce as current statistics rely on a single official database of limited quality. This paper evaluated the completeness and accuracy of crash data collected from multiple sources in a prospective cohort study involving cyclists. METHODS: The study recruited 2438 adult cyclists from New Zealand's largest mass cycling event in November 2006 and another 190 in 2008, and obtained data regarding bicycle crashes that were attended by medical personnel or the police and occurred between the date of recruitment and 30 June 2011, through linkage to insurance claims, hospital discharges, mortality records and police reports. The quality of the linked data was assessed by capture-recapture methods and by comparison with self-reported injury data collected in a follow-up survey. RESULTS: Of the 2590 cyclists who were resident in New Zealand at recruitment, 855 experienced 1336 crashes, of which 755 occurred on public roads and 120 involved a collision with a motor vehicle, during a median follow-up of 4.6 years. Log-linear models estimated that the linked data were 73.7% (95% CI: 68.0%-78.7%) complete with negligible differences between on- and off-road crashes. The data were 83.3% (95% CI: 78.9%-87.6%) complete for collisions. Agreement with the self-reported data was moderate (kappa: 0.55) and varied by personal factors, cycling exposure and confidence in recalling crash events. If self-reports were considered as the gold standard, the linked data had 63.1% sensitivity and 93.5% specificity for all crashes and 40.0% sensitivity and 99.9% specificity for collisions. CONCLUSIONS: Routinely collected databases substantially underestimate the frequency of bicycle crashes. Self-reported crash data are also incomplete and inconsistent. It is necessary to improve the quality of individual data sources as well as record linkage techniques so that all available data sources can be used reliably.
BMC Public Health 05/2013; 13(1):420. · 2.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: INTRODUCTION: Few studies have measured the effect of tobacco bans on secondhand smoke (SHS) exposure in prisons. From June 1, 2011, the sale of tobacco was prohibited in New Zealand prisons. One month later, the possession of tobacco was banned. We studied the indoor air quality before and after this policy was enforced. METHODS: We measured indoor-fine-particulate (PM(2.5)) concentrations using a TSI SidePak photometer. The instrument was placed in a staff base of a New Zealand maximum-security prison, adjacent to four 12-cell wings. Measurements were made before the sales restriction, during this period, and after the ban. Data were summarized using daily geometric means and generalized least squares regression. RESULTS: A total of 7,107 observations were recorded at 5-min intervals, on 14 days before and 15 days after implementation, between 24 May and 5 August. Before the policy was implemented, the geometric mean was 6.58 μg/m(3) (95% CI = 6.29-6.58), which declined to 5.17 μg/m(3) (95% CI = 4.93-5.41) during the sales ban, and fell to 2.44 μg/m(3) (95% CI = 2.37-2.52) after the smoking ban. Regression analyses revealed an average 57% (95% CI = 42-68) decline in PM(2.5) concentrations, comparing the before and after periods.Conclusions:Our study showed a rapid and substantial improvement in indoor air quality after tobacco was banned at a prison. We conclude that prisoners have reduced their smoking in line with the ban, and that a significant health hazard has been reduced for staff and prisoners alike.
Nicotine & Tobacco Research 05/2012; · 2.48 Impact Factor
[show abstract][hide abstract] ABSTRACT: Cycling has the potential to provide health, environmental and economic benefits but the level of cycling is very low in New Zealand and many other countries. Adverse weather is often cited as a reason why people do not cycle. This study investigated temporal and seasonal variability in cycle volume and its association with weather in Auckland, New Zealand's largest city.
Two datasets were used: automated cycle count data collected on Tamaki Drive in Auckland by using ZELT Inductive Loop Eco-counters and weather data (gust speed, rain, temperature, sunshine duration) available online from the National Climate Database. Analyses were undertaken using data collected over one year (1 January to 31 December 2009). Normalised cycle volumes were used in correlation and regression analyses to accommodate differences by hour of the day and day of the week and holiday.
In 2009, 220,043 bicycles were recorded at the site. There were significant differences in mean hourly cycle volumes by hour of the day, day type and month of the year (p < 0.0001). All weather variables significantly influenced hourly and daily cycle volumes (p < 0.0001). The cycle volume increased by 3.2% (hourly) and 2.6% (daily) for 1°C increase in temperature but decreased by 10.6% (hourly) and 1.5% (daily) for 1 mm increase in rainfall and by 1.4% (hourly) and 0.9% (daily) for 1 km/h increase in gust speed. The volume was 26.2% higher in an hour with sunshine compared with no sunshine, and increased by 2.5% for one hour increase in sunshine each day.
There are temporal and seasonal variations in cycle volume in Auckland and weather significantly influences hour-to-hour and day-to-day variations in cycle volume. Our findings will help inform future cycling promotion activities in Auckland.
Environmental Health 03/2012; 11:12. · 2.71 Impact Factor
[show abstract][hide abstract] ABSTRACT: BACKGROUND: We examine the effect of heat waves on mortality, over and above what would be predicted on the basis of temperature alone. METHODS: Present modeling approaches may not fully capture extra effects relating to heat wave duration, possibly because the mechanisms of action and the population at risk are different under more extreme conditions. Modeling such extra effects can be achieved using the commonly left-out effect-modification between the lags of temperature in distributed lag models. RESULTS: Using data from Stockholm, Sweden, and a variety of modeling approaches, we found that heat wave effects amount to a stable and statistically significant 8.1-11.6% increase in excess deaths per heat wave day. The effects explicitly relating to heat wave duration (2.0-3.9% excess deaths per day) were more sensitive to the degrees of freedom allowed for in the overall temperature-mortality relationship. However, allowing for a very large number of degrees of freedom indicated over-fitting the overall temperature-mortality relationship. CONCLUSIONS: Modeling additional heat wave effects, e.g. between lag effect-modification, can give a better description of the effects from extreme temperatures, particularly in the non-elderly population. We speculate that it is biologically plausible to differentiate effects from heat and heat wave duration.
Environmental Health 01/2012; 11:23. · 2.71 Impact Factor
[show abstract][hide abstract] ABSTRACT: This descriptive article examines the potential for student-led initiatives in international health to be better integrated with formal medical education systems. Students have embraced the challenges and opportunities provided by globalisation to take a leadership role on international issues. Medical students are involved with a diverse portfolio of international activities, including work to internationalise the medical curriculum, the establishment of “hands-on” development projects, efforts to promote student exchanges, and engagement with high-level international policy fora. Such experiences not only add to the personal and professional development of the individual student, but also have the potential to contribute to the academic environment of the host institution as well as more broadly influencing the determinants of international health outcomes. There are challenges and risks associated with independent student initiatives, however these risks can be mitigated if institutions work in partnership with their students and peers internationally.
[show abstract][hide abstract] ABSTRACT: To assess regional variations in rates of traffic injuries to pedal cyclists resulting in death or hospital inpatient treatment, in relation to time spent cycling and time spent travelling in a car.
Cycling injuries were identified from the Mortality Collection and the National Minimum Dataset. Time spent cycling and time spent travelling as a driver or passenger in a car/van/ute/SUV were computed from National Household Travel Surveys. There are 16 census regions in New Zealand, some of which were combined for this analysis to ensure an adequate sample size, resulting in eight regional groups. Analyses were undertaken for 1996-99 and 2003-07.
Injury rates, per million hours spent cycling, varied widely across regions (11 to 33 injuries during 1996-99 and 12 to 78 injuries during 2003-07). The injury rate increased with decreasing per capita time spent cycling. The rate also increased with increasing per capita time spent travelling in a car. There was an inverse association between the injury rate and the ratio of time spent cycling to time spent travelling in a car. The expected number of cycling injuries increased with increasing total time spent cycling but at a decreasing rate particularly after adjusting for total time spent travelling in a car.
The findings indicate a 'risk in scarcity' effect for New Zealand cyclists such that risk profiles of cyclists are likely to deteriorate if fewer people use a bicycle and more use a car.
Cooperative efforts to promote cycling and its safety and to restrict car use may reverse the risk in scarcity effect.
Australian and New Zealand Journal of Public Health 08/2011; 35(4):357-63. · 1.64 Impact Factor
[show abstract][hide abstract] ABSTRACT: Adaptation is necessary because climate change has gained considerable momentum. Deep cuts in emissions must be made rapidly to avoid warming of 2° above preindustrial levels but this is most unlikely, given present trends. It is possible that warming may in fact reach 4°C or more by 2100. Risks to health result principally from the effects of climate change on local food production, severity and frequency of storms and floods, threats to water supplies, and the direct effects of heat. The health sector has an important role protecting health in times of climate change. However, other sectors must be involved as well—steps taken in agriculture, urban planning, water and civil defence, for instance, will have implications for prevention of illness and injury. We offer a framework for planning adaptation, taking into account present climate-sensitive health problems, control options, and constraints. WIREs Clim Change 2011 2 271–282 DOI: 10.1002/wcc.103For further resources related to this article, please visit the WIREs website
[show abstract][hide abstract] ABSTRACT: To estimate the effects on health, air pollution and greenhouse gas emissions if short trips (≤7 km) were undertaken by bicycle rather than motor car.
Existing data sources were used to model effects, in the urban setting in New Zealand, of varying the proportion of vehicle kilometres travelled by bicycle instead of light motor vehicle.
Shifting 5% of vehicle kilometres to cycling would reduce vehicle travel by approximately 223 million kilometres each year, save about 22 million litres of fuel and reduce transport-related greenhouse emissions by 0.4%. The health effects would include about 116 deaths avoided annually as a result of increased physical activity, six fewer deaths due to local air pollution from vehicle emissions, and an additional five cyclist fatalities from road crashes. In economic terms, including only fatalities and using the NZ Ministry of Transport Value of a Statistical Life, the health effects of a 5% shift represent net savings of about $200 million per year.
The health benefits of moving from cars to bikes heavily outweigh the costs of injury from road crashes.
Transport policies that encourage bicycle use will help to reduce air pollution and greenhouse emissions and improve public health.
Australian and New Zealand Journal of Public Health 02/2011; 35(1):54-60. · 1.64 Impact Factor
[show abstract][hide abstract] ABSTRACT: The growing health risks associated with greenhouse gas emissions highlight the need for new energy policies that emphasize efficiency and low-carbon energy intensity.
We assessed the relationships among electricity use, coal consumption, and health outcomes.
Using time-series data sets from 41 countries with varying development trajectories between 1965 and 2005, we developed an autoregressive model of life expectancy (LE) and infant mortality (IM) based on electricity consumption, coal consumption, and previous year's LE or IM. Prediction of health impacts from the Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS) integrated air pollution emissions health impact model for coal-fired power plants was compared with the time-series model results.
The time-series model predicted that increased electricity consumption was associated with reduced IM for countries that started with relatively high IM (> 100/1,000 live births) and low LE (< 57 years) in 1965, whereas LE was not significantly associated with electricity consumption regardless of IM and LE in 1965. Increasing coal consumption was associated with increased IM and reduced LE after accounting for electricity consumption. These results are consistent with results based on the GAINS model and previously published estimates of disease burdens attributable to energy-related environmental factors, including indoor and outdoor air pollution and water and sanitation.
Increased electricity consumption in countries with IM < 100/1,000 live births does not lead to greater health benefits, whereas coal consumption has significant detrimental health impacts.
Environmental Health Perspectives 02/2011; 119(6):821-6. · 7.26 Impact Factor
[show abstract][hide abstract] ABSTRACT: The risk of injury is one of the major barriers to engaging in cycling. We investigated exposure-based rates and profiles of traffic injuries sustained by pedal cyclists that resulted in death or hospital inpatient treatment in New Zealand, one of the most car dependent countries.
Pedal cyclist traffic injuries were identified from the Mortality Collection and the National Minimum Dataset. Total time spent cycling was used as the measure of exposure and computed from National Household Travel Surveys. Analyses were undertaken for the periods 1988-91, 1996-99 and 2003-07 in relation to other major road users and by age, gender and body region affected. A modified Barell matrix was used to characterise the profiles of pedal cyclist injuries by body region affected and nature of injury.
Cyclists had the second highest rate of traffic injuries compared to other major road user categories and the rate increased from 1996-99 to 2003-07. During 2003-07, 31 injuries occurred per million hours spent cycling. Non-collision crashes (40%) and collisions with a car, pick-up truck or van (26%) accounted for two thirds of the cycling injuries. Children and adolescents aged under 15 years were at the highest risk, particularly of non-collision crashes. The rate of traumatic brain injuries fell from 1988-91 to 1996-99; however, injuries to other body parts increased steadily. Traumatic brain injuries were most common in collision cases whereas upper extremity fractures were most common in other crashes.
The burden of fatal and hospitalised injuries among pedal cyclists is considerable and has been increasing over the last decade. This underscores the development of road safety and injury prevention programmes for cyclists alongside the cycling promotion strategies.
BMC Public Health 10/2010; 10:655. · 2.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: Few cohort studies of the health effects of urban air pollution have been published. There is evidence, most consistently in studies with individual measurement of social factors, that more deprived populations are particularly sensitive to air pollution effects.
Records from the 1996 New Zealand census were anonymously and probabilistically linked to mortality data, creating a cohort study of the New Zealand population followed up for 3 years. There were 1.06 million adults living in urban areas for which data were available on all covariates. Estimates of exposure to air pollution (measured as particulate matter with an aerodynamic diameter less than 10 μm, PM(10)) were available for census area units from a previous land use regression study. Logistic regression analyses were conducted to investigate associations between cause-specific mortality rates and average exposure to PM(10) in urban areas, with control for confounding by age, sex, ethnicity, social deprivation, income, education, smoking history and ambient temperature.
The odds of all-cause mortality in adults (aged 30-74 years at census) increased by 7% per 10 μg/m(3) increase in average PM(10) exposure (95% CI 3% to 10%) and 20% per 10 μg/m(3) among Maori, but with wide CI (7% to 33%). Associations were stronger for respiratory and lung cancer deaths.
An association of PM(10) with mortality is reported in a country with relatively low levels of air pollution. The major limitation of the study is the probable misclassification of PM(10) exposure. On balance, this means the strength of association was probably underestimated. The apparently greater association among Maori might be due to different levels of co-morbidity.
Journal of epidemiology and community health 10/2010; 66(5):468-73. · 3.04 Impact Factor
[show abstract][hide abstract] ABSTRACT: Smoking contributes to the 7 to 8 year gap between Maori and non-Maori life expectancy (2006 Census). To inform current discussions by policy-makers on tobacco control, we estimate life-expectancy in 2040 for Maori and non-Maori, never-smokers and current-smokers. If nobody smoked tobacco from 2020 onwards, then life expectancy in 2040 will be approximated by projected never-smoker life expectancy.
Life-tables by sex/ethnicity/smoking status for 1996-99 were estimated by merging official Statistics New Zealand life-tables, census data and linked census-mortality rate estimates. We specified six modelling scenarios, formed by combining two options for future per annum declines in mortality rates among never-smokers (1.5%/2.5% and 2.0%/3.5% for non-Maori/Maori; i.e. assuming a return to long-run trends of closing ethnic gaps as in pre-1980s decades), and three options for future per annum reductions in the mortality rate difference comparing current to never-smokers (0%, 1% and 2%).
In 1996-1999, current smokers had an estimated 3.9 to 7.4 years less of life expectancy relative to never-smokers. This smoking difference in life expectancy was less among Maori than among non-Maori. If the 2006 census smoking prevalence remains unchanged into the future, we estimate the difference in 2040 between Maori and non-Maori life expectancy will range from 1.8 to 6.1 years across the six scenarios and two sexes (average 3.8). If nobody smokes tobacco from 2020 onwards, we estimate additional gains in life expectancy for Maori ranging from 2.5 to 7.9 years (average 4.7) and for non-Maori ranging from 1.2 to 5.4 years (average 2.9). Going smokefree as a nation by 2020, compared to no change from the 2006 Census population smoking prevalence, will close ethnic inequalities in life expectancy by 0.3 to 4.6 years (average 1.8 years; consistently greater for females).
If smoking persists at current rates it will become an even greater constraint on life expectancy improvements for New Zealanders in the future. Continued increases in life expectancy, and closing of the Maori:non-Maori gaps in life expectancy, would be greatly assisted by the end of tobacco smoking in Aotearoa-New Zealand by 2020.
The New Zealand medical journal 08/2010; 123(1320):26-36.
[show abstract][hide abstract] ABSTRACT: AimTo assess exposure-based risks and profiles of road traffic injuries sustained by pedal cyclists that resulted in death or hospital inpatient treatment in New Zealand.Methods
Traffic cycling injuries were identified from the National Minimum Dataset and Mortality Collection. Total time spent cycling was used as the measure of exposure and computed from National Household Travel Surveys. Analyses were undertaken for the periods 1988–1991, 1996–1999 and 2003–2007. A modified Barell Matrix was used to characterise injury profiles by body region affected and nature of injury.ResultsCyclists had the second highest risk of traffic injuries compared to other major road user categories and the risk increased from 1996–1999 to 2003–2007. During 2003–2007, 31 injuries occurred per million hours spent cycling. Non-collision crashes (40%) and collisions with a car, pick-up truck or van (26%) accounted for two thirds of the injuries. Children and adolescents aged under 15 years were at the highest risk of non-collision crashes. Males had a higher risk of injury compared to females. The rate of traumatic brain injuries fell over the study period; however, injuries to other body parts increased steadily. Traumatic brain injuries were most common in collision cases whereas upper extremity fractures were most common in other crashes.Conclusion
The burden of fatal and hospitalised injuries among pedal cyclists is considerable and has been increasing over the last decade. This underscores the development of road safety and injury prevention programmes for cyclists alongside the cycling promotion strategies.
[show abstract][hide abstract] ABSTRACT: AimTo assess regional differences in the risks of traffic injuries to pedal cyclists that resulted in death or hospital inpatient treatment in relation to time spent cycling and time spent travelling in a carMethods
Cycling injuries were identified from the Mortality Collection and the National Minimum Dataset. Time spent cycling and time spent travelling in a car/van/Ute/SUV as driver or passenger was computed from National Household Travel Surveys. There are sixteen census regions in New Zealand, some of which were combined for this analysis to ensure an adequate sample size, resulting in eight regional groups. Analyses were undertaken for 1996–1999 and 2003–2007.ResultsThe risk of injuries per million hours spent cycling varied widely across regions (ranging from 11 to 33 injuries during 1996–1999 and from 12 to 78 injuries during 2003–2007). The expected number of cycling injuries increased with increasing annual total time spent cycling but at a decreasing rate after adjusting for total time spent travelling in a car. The risk of cycling injuries decreased with increasing annual per capita time spent cycling. However, the risk increased with increasing annual per capita time spent travelling in a car. There was an inverse association between the injury risk and the ratio of time spent cycling to time spent travelling in a car.Conclusion
The findings indicate the ‘risk in scarcity’ effect for New Zealand cyclists, that is, the risk profiles of cyclists will worsen if less people use a bicycle and more use a car.