Improving surveillance for injuries associated with potential motor vehicle safety defects.

OBJECTIVE: To improve surveillance for deaths and injuries associated with potential motor vehicle safety defects. DESIGN: Vehicles in fatal crashes can be studied for indications of potential defects using an "early warning" surveillance statistic previously suggested for screening reports of adverse drug reactions. This statistic is illustrated with time series data for fatal, tire related and fire related crashes. Geographic analyses are used to augment the tire related statistics. RESULTS: A statistical criterion based on the Poisson distribution that tests the likelihood of an expected number of events, given the number of events that actually occurred, is a promising method that can be readily adapted for use in injury surveillance. CONCLUSIONS: Use of the demonstrated techniques could have helped to avert a well known injury surveillance failure. This method is adaptable to aid in the direction of engineering and statistical reviews to prevent deaths and injuries associated with potential motor vehicle safety defects using available databases.

The beta1-integrin cytosolic domain optimizes phospholipase A2-mediated arachidonic acid release required for NIH-3T3 cell spreading.

Inhibition of PLA2 activity and rescue by addition of exogenous AA was used to demonstrate that AA production is essential for integrin-mediated NIH-3T3 murine cell spreading. Both AA release and cell spreading after attachment to a FN substrate were inhibited by the PLA2 inhibitor mepacrine. AA release was essential for signaling spreading since the inhibition of spreading induced by mepacrine was overcome by exogenous AA. Cells ectopically expressing full-length chicken beta1-integrins both released AA and spread fully on a substrate of anti-chicken beta1-integrin monoclonal antibody, and inhibition of PLA2 by mepacrine suppressed both spreading and AA release. Exogenous AA also reversed this mepacrine-induced inhibition of spreading. The role of the beta1-integrin cytosolic domain in AA release was examined by comparing responses of cells expressing full-length chicken beta1-integrins versus cells expressing a deletion mutant chicken beta1-integrin with a truncated cytosolic domain. Cells expressing a truncated chicken beta1-integrin released significantly less AA and failed to spread on the anti-chicken beta1-integrin antibody substrate. Furthermore, clustering full-length receptors with soluble antibody stimulated greater AA release than clustering of receptors having truncated cytosolic domains. These data suggest the beta1-integrin cytosolic domain is required for optimal PLA2 activation to produce AA necessary for cell spreading.

The effect of passenger load on unstable vehicles in fatal, untripped rollover crashes.

Consumers may be unaware of the risk of rollover crashes posed by passenger loads in vehicles with poor roll stability. This analysis demonstrates that certain sports utility vehicles and small pickup trucks have designs that are so unstable that the weight of the passengers in the vehicle affects its propensity to roll over. This effect occurs even though the weight of the loaded vehicle is less than the manufacturer's gross vehicle weight rating. The risk of a fatal, "untripped" rollover crash in vehicles with low roll stability is increased as each passenger is added to the vehicle load.

Predicting injury risk with "New Car Assessment Program" crashworthiness ratings.

The relationship between crashworthiness ratings produced by the National Highway Traffic Safety Administration's (NHTSA's) New Car Assessment Program (NCAP) and the risk of incapacitating injury or death for drivers who are involved in single-car, fixed-object, frontal collisions was examined. The results are based on 6,405 such crashes from the Motor Vehicle Traffic Accident file of the Texas Department of Highways and Public Transportation. The risk of injury was modeled using logistic regression taking into account the NCAP test results for each individual model of car and the intervening effects of car mass, age of the driver, restraint use, and crash severity. Three measures of anthropometric dummy response, Head Injury Criterion (HIC), Chest Deceleration (CD), and femur load were used to indicate vehicle crash test performance. The results show that there is a significant relationship between the results of the NCAP tests and the risk of serious injury or death in actual single-car frontal accidents. In terms of overall injury, chest deceleration was a better predictor than the Head Injury Criterion. For restrained drivers, crash severity, driver age, and chest deceleration were significant parameters for predicting risk of serious injury or death; the risk of injury decreased as chest deceleration decreased. The results were similar for unrestrained drivers although vehicle mass and femur load were also significant factors in the model. The risk of overall injury decreased as chest deceleration decreased but appeared to decrease as femur load increased.

Historical changes in motor vehicle death rates among the elderly.

Motor vehicle death rates among the elderly decreased substantially between 1940 and 1980, while the number of registered motor vehicles in the United States increased fourfold and death rates from motor vehicle injury changed little for the entire population. The annual death rate per 100,000 males aged 75-79 declined from 120 in 1940 to 41 in 1980. Much of the decrease can be attributed to reduced pedestrian deaths. Rates for other elderly age and sex groups showed similar patterns but the rates were lower and the changes smaller. Displaying age-specific motor vehicle death rates by birth cohort provides a graphic demonstration that these death rates have decreased markedly for all age groups 60 and older. Implications and possible causes of this decrease are discussed.

County mapping of injury mortality.

Death rates for injuries were mapped by county in order to identify high-risk geographic areas. Overall rates of unintentional injury death were high in rural areas, especially in the West, and in low-income southern counties. Homicides, primarily due to firearms, had high rates throughout the South; elsewhere, homicide rates were high in large cities but not in suburban counties. Southern counties also had high rates of housefire mortality. Drowning rates for young children were high on the West Coast and in Florida, and were high for the population as a whole in the Mississippi Delta. Mapping by county is a potentially powerful tool for identifying high-risk areas and developing preventive measures.

Changing patterns in motor vehicle crash mortality: 1940-1980.

Overall motor vehicle mortality rates in the United States varied little between 1940 (26 deaths per 100,000 per year) and 1980 (23 deaths per 100,000 per year). However, the distribution of motor vehicle deaths by age, sex, and road user status has changed considerably. Among the elderly there has been a substantial increase in motor vehicle death rates. The result of these changes, and of the altered age structure of the population, is that the number of years of life lost to motor vehicle crash injury before age 70 has increased 84 percent between 1940 and 1980.

Geographic variations in mortality from motor vehicle crashes.

Using a new technique to study the mortality associated with motor vehicle crashes, we calculated population-based death rates of occupants of motor vehicles during the period 1979 through 1981 and mapped them according to county for the 48 contiguous states of the United States. Mortality was highest in counties of low population density (r = 0.57; P less than 0.0001) and was also inversely correlated with per capita income (r = 0.23; P less than 0.0001). Death rates varied more than 100-fold; for example, Esmeralda County, Nevada, with 0.2 residents per square mile (2.6 km2), had a death rate of 558 per 100,000 population, as compared with Manhattan, New York, with 64,000 residents per square mile and a death rate of 2.5 per 100,000. Differences in road characteristics, travel speeds, seat-belt use, types of vehicles, and availability of emergency care may have been major contributors to these relations.

Projected mortality from injuries.

Illustrative projections of mortality from injuries, all accidents and motor vehicle crashes were developed based on current mortality rates. If exposure to existing injury sources is unchanged and unless more effective injury prevention countermeasures are employed, 8 million injury deaths may be expected to occur among the resident population of the United States alive in 1980. These deaths include nearly 2 million motor vehicle fatalities and more than 5.6 million deaths from all accidents.

A nutritional analysis of the Food Stamp Program.

Conflicting claims made both for and against the Food Stamp program have never been based on empirical evidence of its effects on the adequacy and the quality of diets of poor people. In this study, individual diets are measured against dietary standards appropriate for individuals and models of nutritional adequacy are constructed which make possible a determination of the program's impact on many different components of human nutrition. Two types of multiple regression models of nutrient sufficiency--ratios of dietary intake to standard as well as nutrient densities--were developed with dietary recall data from 181 and 195 subjects, respectively. These subjects were selected in a random, probability sample of a low-income area of Tulsa. Oklahoma in 1978 and all had annual household incomes which placed them at or below the poverty level. Separate models were developed for each of six nutrients, calories, protein, calcium, iron, vitamin A and vitamin C, and a large number of covariates were included in these models to isolate the effects due to program participation. The results suggest that the effects of food stamps are not uniformly positive nor are they similar to the effects which could be expected under a less expensive system of direct cash payments.