Pre-licensed driving experience and car crash involvement during the learner and restricted, licence stages of graduated driver licensing: Findings from the New Zealand drivers study.

OBJECTIVE: The aim of this study was to determine whether pre-licence driving experiences, that is driving before beginning the licensing process, increased or decreased crash risk as a car driver, during the learner or the restricted licence stages of the graduated driver licensing system (GDLS). METHOD: Study participants were 15-24 year old members of the New Zealand Drivers Study (NZDS) - a prospective cohort study of newly licensed car drivers. The interview stages of the NZDS are linked to, the three licensing stages of the GDLS: learner, restricted and full. Baseline demographic (age, ethnicity, residential location, deprivation), personality (impulsivity, sensation seeking, aggression) and, behavioural data, (including pre-licensed driving behaviour), were obtained at the learner licence interview. Data on distance driven and crashes that occurred at the learner licence and restricted licence stages, were reported at the restricted and full licence interviews, respectively. Crash data were also obtained from police traffic crash report files and this was combined with the self-reported crash data. The analysis of the learner licence stage crashes, when only supervised driving is allowed, was based on the participants who had passed the restricted licence test and undertaken the NZDS, restricted licence interview (n=2358). The analysis of the restricted licence stage crashes, when unsupervised driving is first allowed, was based on those who had passed the full licence test and completed the full licence interview (n=1428). RESULTS: After controlling for a range of demographic, personality, behavioural variables and distance driven, Poisson regression showed that the only pre-licence driving behaviour that showed a consistent relationship with subsequent crashes was on-road car driving which was associated with an increased risk of being the driver in a car crash during the learner licence period. CONCLUSION: This research showed that pre-licensed driving did not reduce crash risk among learner or restricted licensed drivers, and in some cases (such as on-road car driving) may have increased risk. Young people should be discouraged from the illegal behaviour of driving a car on-road before licensing.

Reducing young driver crash casualties in Great Britain - use of routine police crash data to estimate the potential benefits of graduated driver licensing.

Crashes involving young drivers (YD) cause significant morbidity and mortality in Great Britain (GB). Graduated Driver Licensing (GDL) is used in some countries to address this. This study assessed potential casualty and cost savings of possible GDL programmes in GB. Police road crash data were analysed to identify YD crashes at night or while carrying passengers. These data were then used to estimate the potential effects of GDL. 314,561 casualties and 3469 fatalities occurred in YD crashes. 25.1% of YD crashes occurred between 9 pm and 6 am and 24.4% occurred with a 15- to 24-year old passenger in the car. A 'strict' form of GDL in GB (night time restriction 9 pm-6 am, no 15-24 year old passengers) with 50% compliance would prevent 114 deaths and 872 serious casualties each year. The estimated value of prevention is £424M pa. A 'less strict' form of GDL (night time restriction 10 pm-5 am, maximum of one 15-19 year old passenger) with 50% compliance would prevent 81 deaths and 538 serious injuries. The estimated value of prevention is £273M pa. Implementing GDL in GB could save significant numbers of lives. Public health organisations have a duty to advocate for such legislation.

Age, period and cohort effects on the incidence of motorcyclist casualties in traffic crashes.

OBJECTIVES: (1) Estimate age, period and cohort effects for motorcyclist traffic casualties 1979-2008 in New Zealand and (2) forecast the incidence of New Zealand motorcycle traffic casualties for the period 2019-2023 assuming future age, cohort and period effects, and compare these with an estimate based on simple linear extrapolation. METHODS: Age-period-cohort (APC) modelling was used to estimate the individual effects of age, period and cohort after adjusting for the other two factors. Forecasting was produced for three period-effect scenarios. RESULTS: After adjusting for cohort and period effects, 15-19-year-olds have substantially elevated risk. The period effect reduced in significance over time until the last period, 2004-2008, where the risk was higher than the preceding period. The 10-year cohorts born 1949-1958, 1954-1963, 1959-1968 and 1964-1973, had elevated risk. The forecasting, based on APC modelling, resulted in the lowest estimates of the future incidence being approximately one-third that of the highest estimate (6641). CONCLUSION: Trends in motorcycle casualties have been influenced by significant independent age, period and cohort effects. These need to be considered in forecasting future casualties. The selection of the period effect has a significant impact on the estimates. Which period-effect scenario readers choose to accept depends on their views about a wide range of factors which might influence motorcycle use and crash risk over time.

Validity of using linked hospital and police traffic crash records to analyse motorcycle injury crash characteristics.

Linking hospital discharge and police traffic crash records has been used to provide information on causes and outcomes for hospitalised traffic crash cases. Motorcyclists are particularly vulnerable to injury in a traffic crash, but no published linkage studies have reported in detail on this road user group. The present study examined motorcycle traffic crash injury cases in New Zealand in 2000-2004 by probabilistically linking national hospital discharge records with police traffic crash reports. Injury cases had to have spent at least one night in hospital before being discharged and were defined as serious or moderate based on their International Classification of Disease Injury Severity Scores (ICISS). Despite a robust linkage process, only 46% of cases could be linked to a police record; 60% of the serious injuries and 41% of the moderate. The low linkage was most likely due to under-reporting of crashes to or by the police. While moderate injury cases were expected to be under-reported, the level of under-reporting of cases with serious threat-to-life injuries is concerning. To assess whether the linked dataset could provide valid information on the crash circumstances and injury outcomes of hospitalised motorcycle crash cases, the characteristics of the linked and unlinked hospital discharge cases were compared using chi-square tests and multivariate logistic regression. Serious injury cases were less likely to be linked if only one vehicle was involved, or the injured riders and passengers were younger than 20 years or spent less than one week in hospital. For moderate injury cases, there were also differences in linkage by injured body region and crash month. While these discrepancies need to taken into consideration when interpreting results, the linked hospital-police dataset has the potential to provide insights into motorcycle crash circumstances and outcomes not otherwise obtainable.

A longitudinal examination of the relationship between adolescent problem behaviors and traffic crash involvement during young adulthood.

Previous research examining the relationship between adolescent problem behaviors and young adult traffic outcomes (crashes, convictions, risky driving) has produced differing results. Possible reasons for this may be the heterogeneity of the crash outcomes (from minor fender-benders to fatal crashes), the gender of the driver, and/or the age of the driver. The aim of this research was to investigate the relationship between adolescent problem behaviors and young adult crashes to determine the extent to which the above factors influenced this relationship. This study was part of the Dunedin Multidisciplinary Health and Development Study (DMHDS), which is a longitudinal study of a cohort (n = 1,037) born in Dunedin, New Zealand, from April 1972 to March 1973. This cohort has been followed up regularly since birth, and the data for the present research were obtained at the 18-, 21-, and 26-year-old follow-up interviews. The problem behaviors examined were those identified by Jessor in the theory of problem behavior, namely, tobacco smoking, marijuana use, alcohol use, delinquent behavior, and unsafe sexual behavior. Data for these measures were obtained in personal interviews when the cohort was aged 18 years. The self-reported crash data were obtained at the age 21 and age 26 follow-up interviews. Driving exposure, academic qualifications, employment, being a parent, and marital status were included as potential confounders. The results show that involvement in adolescent problem behaviors predicted crash involvement at age 21 for the females but not the males and at age 26 for the males but not the females. Possible explanations for these differences by age and gender are discussed.

Minimum purchasing age for alcohol and traffic crash injuries among 15- to 19-year-olds in New Zealand.

OBJECTIVES: In 1999, New Zealand lowered the minimum purchasing age for alcohol from 20 to 18 years. We tested the hypothesis that this increased traffic crash injuries among 15- to 19-year-olds. METHODS: Poisson regression was used to compute incidence rate ratios for the after to before incidence of alcohol-involved crashes and hospitalized injuries among 18- to 19-year-olds and 15- to 17-year-olds (20- to 24-year-olds were the reference). RESULTS: Among young men, the ratio of the alcohol-involved crash rate after the law change to the period before was 12% larger (95% confidence interval [CI]=1.00, 1.25) for 18- to 19-year-olds and 14% larger (95% CI=1.01, 1.30) for 15- to 17-year-olds, relative to 20- to 24-year-olds. Among young women, the equivalent ratios were 51% larger (95% CI=1.17, 1.94) for 18- to 19-year-olds and 24% larger (95% CI=0.96, 1.59) for 15- to 17-year-olds. A similar pattern was observed for hospitalized injuries. CONCLUSIONS: Significantly more alcohol-involved crashes occurred among 15-to 19-year-olds than would have occurred had the purchase age not been reduced to 18 years. The effect size for 18- to 19-year-olds is remarkable given the legal exceptions to the pre-1999 law and its poor enforcement.

Identifying predictors of persistent non-alcohol or drug-related risky driving behaviours among a cohort of young adults.

This study sought to identify adolescent risk factors that predicted persistent risky driving behaviours among young adults. It was part of a longitudinal study of a birth cohort (474 males and 459 females). The potential predictors were self-reported data obtained at ages 15, 18, 21 years (academic qualifications, personality, mental health, anti-social behaviour and driving behaviour). The risky driving behaviour outcomes were obtained at ages 21 and 26 years and included driving fast for thrills, taking deliberate risks for fun, excessive speed, dangerous overtaking, and close following (tailgating). Persistent risky drivers were defined as those who often, or fairly often engaged in a behaviour at both ages. A minority of males and very few females were classified as persistent risky drivers. Among the males, the factors that predicted at least one, or more of the outcomes were the personality trait of low constraint (i.e. low scores for control, harm avoidance, and traditionalism), aggressive behaviour, and cannabis dependence. These are characteristics to be borne in mind when developing programmes for young drivers that aim to deter the development of persistent risky driving behaviour.

Identifying factors that predict persistent driving after drinking, unsafe driving after drinking, and driving after using cannabis among young adults.

UNLABELLED: The main aim of this study was to identify adolescent/young adulthood factors that predicted persistent driving after drinking, persistent unsafe driving after drinking, and persistent cannabis use and driving among young adults. It was a longitudinal study of a birth cohort (n=933, 474 males and 459 females) and was based on data collected at ages 15, 18, 21 and 26 years. At each of these ages members of the cohort attended the research unit for a personal interview by a trained interviewer, using a standardised questionnaire. For this study, the data for the outcome measures (persistent driving after drinking, persistent unsafe driving after drinking, and persistent driving after using cannabis) were obtained at ages 21 and 26 years. The main explanatory measures were collected at ages 15, 18, 21 years and included demographic factors (academic qualifications, employment, parenting); personality measures; mental health measures (substance use, cannabis dependence, alcohol dependence, depression); anti-social behaviour (juvenile arrest, aggressive behaviour, court convictions); early driving behaviour and experiences (car and motorcycle licences, traffic crashes). The analyses were conducted by gender. The results showed that females who persisted in driving after drinking (13%, n=61) were more likely than the others to have a motorcycle licence at 18. The males who persisted in driving after drinking (28%, n=135) were more likely than the other males to have some school academic qualifications and to be employed at age 26. Compared to the other males, those who persisted in unsafe driving after drinking (4%, n=17) were more likely to be aggressive at 18 and alcohol dependent at 21. Only six (1%) females persisted in unsafe driving after drinking so regression analyses were not conducted for this group. For persistent driving after using cannabis, the univariate analyses showed that females who persisted with this behaviour tended to have high substance use at 18, cannabis dependence at 21, police contact as a juvenile, and to be a parent at 21. For this group, because of the small numbers (3%, n=13) multivariate analyses were not appropriate. For the males who persisted in driving after using cannabis (14%, n=68) a wide range of variables were significant at the univariate stage. The multivariate analysis showed that the most important factors were dependence on cannabis at 21, at least one traffic conviction before 21, a non traffic conviction before 18, and low constraint at 18. CONCLUSION: These results show different characteristics were associated with persistence in each of these outcome behaviours. This indicates that different approaches would be required if intervention programmes were to be developed to target these behaviours.