I. Barry Pless

Effectiveness of helmets in skiers and snowboarders: case-control and case crossover study

Abstract Objective To determine the effect of helmets on the risk of head and neck injuries in skiers and snowboarders. Design Matched case-control and case crossover study. Setting 19 ski areas in Quebec, Canada, November 2001 to April 2002. Participants 1082 skiers and snowboarders (cases) with head and neck injuries reported by the ski patrol and 3295 skiers and snowboarders (controls) with non-head or non-neck injuries matched to cases at each hill. Main outcome measures Estimates of matched odds ratios for the effect of helmet use on the risk of any head or neck injury and for people requiring evacuation by ambulance. Results The adjusted odds ratio for helmet use in participants with any head injury was 0.71 (95% confidence interval 0.55 to 0.92), indicating a 29% reduction in the risk of head injury. For participants who required evacuation by ambulance for head injuries, the adjusted odds ratio for helmet use was 0.44 (0.24 to 0.81). Similar results occurred with the case crossover design (odds ratio 0.43, 0.09 to 1.83). The adjusted odds ratio for helmet use for participants with any neck injury was 0.62 (0.33 to 1.19) and for participants who required evacuation by ambulance for neck injuries it was 1.29 (0.41 to 4.04). Conclusions Helmets protect skiers and snowboarders against head injuries. We cannot rule out the possibility of an increased risk of neck injury with helmet use, but the estimates on which this assumption is based are imprecise.

Determinants of weight and adiposity in the first year of life

To overcome methodologic defects (failure to control for confounding factors, univariate statistical analyses) in previous studies of etiologic determinants of childhood adiposity, we carried out a prospective cohort study of 462 healthy, full-term infants observed from birth to 12 months. Postpartum, we obtained sociodemographic data and administered two recently validated scales of maternal attitudes toward feeding and infant body habitus. Parental heights and weights and infant feeding variables were determined by interview, and at 6 and 12 months we measured height and weight and triceps, subscapular, and suprailiac skinfolds. Multiple regression analysis was used to determine independently predictive factors for weight, body mass index (BMI = weight/height), and the sum of the three skinfold measurements. Birth weight, sex, age at introduction of solid, and duration of breast-feeding were all significant predictors of weight at 12 months (r2 = 0.296, P less than 0.0001). Significant determinants for BMI included birth weight, duration of breast-feeding, sex, and IBH (r2 = 0.125, P less than 0.0001); those for total skinfold were age at introduction of solid foods and birth weight (r2 = 0.038, P = 0.002). Similar results were obtained at 6 months, although slightly less of the variance was explained. We conclude that the ability to predict which babies will be heavy or obese during the first year is limited. Breast-feeding and delayed introduction of solid foods do offer some protective effect, however, and thus efforts to encourage these practices may be reaping some benefit.

Sleep patterns and problems in adolescents

A sleep questionnaire was administered to 390 students in an urban high school. Total sleep hours per week appeared to decrease between the ages of 12 and 18 years. In general, girls slept more than boys. The quality of sleep and the perception of sleep adequacy also decreased with age. Reporting of the occasional use of sleep medications and alcohol at bedtime was 4.6% and 10.5%, respectively. These findings suggest that sleep problems among adolescents represent normal physiologic processes as well as some serious disturbances that may reflect the social pressures prevalent during adolescence.

Geographical and socio-ecological variations of traffic accidents among children

This paper deals with geographical and socio-ecological variations of pedestrian and cyclist accidents (n = 1233) among children (less than 15 years) on the Island of Montreal. The model includes variables on each child and his behavior when the accident happened and other temporal and spatial characteristics; environmental and socio-ecological data on the areas in which accidents occurred were also recorded. Descriptive, spatial and comparative analyses show specific patterns of location and occurrence of accidents. Factor analysis identifies the structure of characteristics linked to high accident areas for childrens traffic accidents. A strong similarity between zone characteristics emerged from the factor analysis for both types of accident. Only a few census tracts (between 9% to 13%) are high accident areas, but they are very concentrated spatially, and for some of them (2% for pedestrians and 4% for cyclists) the rate is five to eight times higher than for the rest of the urban area. Population structure and density factors contribute 40% of the variation in accident rates. In terms of numbers, fewer children were injured as cyclists than as pedestrians, and more boys than girls are involved in these accidents. Accidents occur under good conditions of visibility and on straight streets. Parked cars in school areas are also a sign of danger. Difficulties in interpreting information on directions and speed of moving vehicles are associated with high accident frequencies, particularly for young pedestrians (6-7 years).

Clinical assessment: physical and psychological functioning.

This article has provided evidence that children with chronic disorders of all kinds are at increased risk for psychosocial disturbances. That they are also likely to experience some degree of physical disability is self-evident. Accordingly, in the comprehensive care provided for these children the pediatrician is obliged to attempt to assess the status of functioning in these domains. A variety of methods for doing so in the context of a busy office practice has been presented.

For and againstDoes risk homoeostasis theory have implications for road safetyForAgainst

# Does risk homoeostasis theory have implications for road safety {#article-title-2} Risk homoeostasis (also called risk compensation) theory predicts that, as safety features are added to vehicles and roads, drivers tend to increase their exposure to collision risk because they feel better protected. Gerald Wilde provides evidence for it and suggests that it should be used to inform road safety strategies. Leon Robertson and Barry Pless, however, argue that the evidence is deeply flawed and that the theory is little better than an excuse for doing nothing # For {#article-title-3} Anyone wishing to reduce the risk of misfortune on the road to zero can do so by never using the roads, but that person would also miss all the benefits accruing from road travel and thus live a greatly diminished life. Suboptimal risk taking also occurs if a person underestimates or overestimates the danger of a given activity, because that person would either take too much risk or too little for greatest net benefit. A person learns to assess risk by perceiving the outcomes of decisions. Our intuitive assessment of risk is honed by our experience and that of others, sometimes communicated through the mass media. This feedback will thus confirm or correct a persons perception of the size of the four utility factors that determine the optimal (or target) level of risk (see box). #### Theory of risk homoeostasis While some actions entail more danger (probability×magnitude of loss) than others, there is no behaviour without some risk. The challenge, therefore, is to optimise rather than eliminate risk. This optimal, or target, level of risk is that which maximises the overall benefit (probability×amount). Four utility factors determine the target level of risk: The first two factors increase …

Factors related to the frequency of citation of epidemiologic publications

Background Previous studies have demonstrated that the frequency with which a publication is cited varies greatly. Our objective was to determine whether author, country, journal, or topic were associated with the number of times an epidemiological publication is cited. Methods We used outcome-based sampling and investigated one public health issue – child injury prevention, and one clinical topic – coronary artery disease (CAD) prevention. Using the Institute for Scientific Informations (ISI) Web of Science® databases, we limited searches to full articles involving humans published in English between 1998 and 2004. We calculated the citation rate and, after frequency-matching on year of publication, selected the 36 most frequently cited and 36 least frequently cited articles per year, for a total of 252 highly-cited and 252 infrequently-cited articles per topic area (child injury prevention and CAD prevention). Results Highly-cited articles in both CAD and child injury prevention were more likely to be published in medium or high impact journals or in journals with medium or high circulations. They were also more likely to be published by authors from U.S. institutions. Among articles examining CAD prevention, the highly-cited articles often involved risk factors, and the association between topics and frequency of citation persisted after adjusting for impact factor. Among articles addressing child injury prevention, topic was not statistically associated with citation. Conclusion Journal and country appear to be the factors most strongly associated with frequency of citation. In particular, highly-cited articles are predominantly published in high-impact, high-circulation journals. The factors, however, differ somewhat depending on the area of research the journals represent. Among CAD prevention articles, for example, topic is also an important predictor of citation whereas the same is not true for articles addressing injury prevention. Condensed Abstract Our objective was to determine whether author, country, journal, or topic were associated with the number of times an epidemiological publication is cited. We used outcome-based sampling and investigated one public health issue, child injury prevention, and one clinical topic, coronary artery disease (CAD) prevention. Using the Institute for Scientific Information (ISI) Web of Science® databases, we limited searches to full articles involving humans published in English between 1998 and 2004. We calculated the citation rate and, after frequency-matching on year of publication, selected the 36 most frequently cited and 36 least frequently cited articles per year, for a total of 252 highly-cited and 252 infrequently-cited articles per topic area (child injury prevention and CAD prevention). Highly-cited articles in both CAD and child injury prevention were more likely to be published in medium or high impact journals or in journals with medium or high circulations. They were also more likely to be published by authors from U.S. institutions. Among articles examining CAD prevention, the highly-cited articles often involved risk factors, and the association between topics and frequency of citation persisted after adjusting for impact factor. Among articles addressing child injury prevention, topic was not statistically associated with citation.

Preschool behavior disorders: Their prevalence in relation to determinants

The occurrence of behavior disorders was investigated in a prospectively followed 3-year-old birth cohort. Of 1116 eligible children, the parents of 918 were successfully contacted. All agreed to complete a telephone interview and were mailed a Childhood Behavior Checklist (CBCL) standardized for 2- to 3-year-old children; 756 (82%) returned the CBCL. The prevalence of one or more of the deviant behavior syndromes identified by the CBCL was 11.1%. From a number of subject characteristics recorded throughout infancy, age-specific determinants for the occurrence of these deviant behaviors were identified. Characteristics most consistently associated with preschool psychopathology included the mothers ill health and lack of social support, the presence of chronic illness in the child, and the frequent use of hospital emergency services. These and other determinant (risk) indicators were entered into logistic regression (LR) models to derived adjusted relative risk estimates for the occurrence of a behavior disorder. The derived LR equations emphasize the important role of both the mother as well and the father and the health of the child.

Helmet Use and Risk of Neck Injury in Skiers and Snowboarders

In a case-control study, the authors examined the relation between helmet use and neck injury among Québec, Canada, skiers and snowboarders using 10 years of ski patrol data (1995-1996 to 2004-2005). Cases were defined as persons with any neck injury (n = 2,986), an isolated neck injury requiring ambulance evacuation (n = 522), or a cervical spine fracture or dislocation (n = 318). The control group included persons with non-head, non-neck injuries (n = 97,408) in an unmatched analysis. The authors also matched cases with controls injured at the same ski area, during the same activity (skiing vs. snowboarding), and during the same season. Helmet use was the primary exposure variable. For the unmatched analysis, the authors used unconditional logistic regression and adjusted for clustering by ski area and other covariates. They used conditional logistic regression for the matched analysis. Multiple imputation was used to address missing values. The adjusted odds ratio was 1.09 (95% confidence interval (CI): 0.95, 1.25) for any neck injury, 1.28 (95% CI: 0.96, 1.71) for isolated ambulance-evacuated neck injuries, and 1.02 (95% CI: 0.79, 1.31) for cervical spine fractures or dislocations. Similar results were found in the conditional logistic regression analysis and in analyses restricted to children under age 11 years. These results do not suggest that helmets increase the risk of neck injuries among skiers and snowboarders.

Pedestrian injuries to children and youth

Prevention of pedestrian injuries constitutes a most difficult problem, involving not only driver and pedestrian behavior, but also the design of streets, highways, and automobiles. The epidemiology of these injuries is assessed, using the host-agent-environment model, and approaches to prevention are presented, from child behavior modification to engineering.