Health and traffic safety behaviors in the U.S.A :

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1 Health and traffic safety behaviors in the U.S.A : David Shinar*, Richard Com pton** and Edward M ilton *Ben Gurion University of the Negev, Israel **National Highway Traffic Safety Administration, U.S. Department of Transportation ***, National Highway Traffic Safety Administration, U.S. Department o f Transportation A B ST R A C T The purpose of this project was to determine the levels of practice of health and traffic safety behaviors during the period , and determine the trends that have occurred over that period as assessed by Louis Harris surveys conducted annually for Prevention magazine on a representative sample of 1250 people of the U.S. adult population.from the original index - Prevention Index - two sub-indices were developed. A Health Index and a Safety Index. The Safety Index reflects the level of practice of three safe driving behaviors (wearing safety belts, avoiding drinking and driving, and observing the speed limit), and the Health Index reflects health habits such as not drinking, not smoking, exercising, dieting, etc. The principal results showed that there is only a weak association among the individual health behaviors, among the individual safety behaviors, and between the two sets of behaviors. Over the eight year study period the improvement in health habits has been practically insignificant, whereas the improvement in safety habits has been substantial and statistically significant. The greatest and most consistent increase was in the use of safety belts, with the reported percent who use it all the time increasing from 42% in 1985 to 72% in 1992; i.e., a relative increase of nearly 75%! There was also a consistent but smaller positive trend in refraining drinking and driving, from 71% reporting they never drink and drive in 1985 to 78% in Still, it is noteworthy that by 1992 nearly 80% o f the people reported they never drink and drive. Finally obeying the speed limit did not improve over the 8-year period. IN T R O D U C T IO N Since 1983 the Louis Hands & Associates Company has been conducting an annual telephone survey on "Health and Safety" using a representative sample of American adults. The annual surveys were conducted on a random sample of 1250 adults living in the U.S.. The healthrelated questions included habits such as smoking, exercising, drinking, dieting, weight control, stress control, dental and medical examinations, sleep habits, vitamin use, etc. The safety-related questions include behaviors related to avoidance o f home accidents, as well as

2 driving safety questions related to speeding, drinking and driving, and use of occupant protection. The objectives of this study was to analyze the survey data for the years in order to identify (1) Health related and traffic safety-related trends in driver attitudes and reported behaviors over the past 8 years, (2) Associations between different indicators of traffic safety knowledge, attitudes, and behaviors, and (3) Health-related behaviors that are closely linked with safe driving behaviors related to the use o f occupant protection, responsible drinking, and speed control. This report will focus on the alcohol-related findings. SURVEY M ETHOD AND ANALYTICAL APPROACH The sam ple. The study consisted of annual representative samples of 1250 U.S. adults who responded to the Louis Harris survey questions, from 1985 to Com bined Indexes: the Prevention Index (P I), the H ealth Index (H I), and the Safety Index (SI). Three combined indexes of health and safety are used here: 1. The Prevention Index (PI) was originally developed by Louis Harris, Inc. to provide a composite measure of 21 individual actions people take to avoid diseases and accidents. The measures include total abstinence from smoking, not smoking in bed, wearing seat belts, not driving and drinking, having a smoke detector at home, socializing regularly, exercising frequently, drinking alcohol moderately, avoiding home accidents, limiting fat in diet, maintaining proper weight, obeying speed limits, taking an annual blood pressure test, controlling stress, and consuming fiber. 2. The health index (HI) was developed specifically for the present analysis by considering six of the highly ranked health promoting behaviors, included in the PI, that had been consistently included in all the annual surveys: these behaviors include not smoking, exercising regularly, avoiding foods with high fat content, avoiding high cholesterol foods, having regular blood pressure checks, and seeing a dentist regularly. 3. The Safety Index (SI) was also specifically developed for the present study, and the logic used was similar to that of the HI. The SI included the three PI driving safety-related behaviors that were consistently included in all of the annual surveys: avoiding drinking before driving, using safety belts, and observing the speed limits

3 Analytical O bjectives and Approach The analyses focused on (1) Trends in highway safety knowledge, attitudes, and behaviors, (2) Relationships among different traffic safety behaviors and attitudes, and (3) Relationships between health habits and safe driving habits and attitudes. RESULTS AND DISCU SSIO N This report focuses on the associations between health-related behaviors and traffic safetyrelated behaviors, with particular emphasis on drinking and driving.lt should be remembered that all of the frequencies, trends, and associations are discussed below are based on self reports. General C haracteristics o f the Sample In terms of the sample's demographics, the following characteristics remained relatively stable, and year-to-year changes variations were not significant percent of the respondents were males; percent were white, and % were black; and 90.5% percent reported they "drive now" (95.2% of the males and 85.9% of the females, Chi Square = , pc.001). The relationships between age and safety were significant (p<.001) for each of the three surveyed safety behaviors, and are depicted in Figure 1. They can be summarized as follows: 1. Safety belt use. Percent using safety belts all the time increased monotonically from 50.0% of those 20 or under to 63.1% of those 65 years old or older. 2. Observing the speed limit. Percent observing the speed limit all the time increased monotonically from 25.3% o f those 20 or under to 66.7% o f those 65 years old or older. 3. Drinking and driving. Percent who never drink and drive reflected a U shaped curve with the highest rates for the youngest and the oldest drivers (86.3% and 89.7%, respectively). The reported rate was relatively constant at seventy percent for all other age groups ( %). The reported drinking and driving rate for those under 21 is probably an underestimate, since these respondents know that it is illegal for them to drink at all. D rinking and Driving. 75.8% said they never drink and drive, 21.4% said they sometime drink and drive, and 2.8% said they drink and drive all the time. Men were more likely to report drinking and driving, with 68.2% reporting they never drink and drive compared to 84.0% of the women (Chi Square = 276, pc.001)

4 Figure 1 : the R elationship between O bserving the Speed L im it, Not D rinking and D riving, U sing Safety B elts, and A ttitudes tow ards O ccupant R estraint D e v ic e s. 1DQ Age and Traffic Safety Behaviors BD m a oa- / % a 4D - / Legend u»o Scdaty Belt O t a. 5 p M 4 Lfflt D un'l D r ln b lv I n c t M O W-94 9 M * * Apt The three behaviors and attitudes were significantly positively associated with each other. 1. O f those who reported using safety belts all the time, 78.4% said they never drink and drive, while of those who said they never used safety belts 69.1% said they drink and drive (Chi Square = 70.01, pc.001) 2. Of those who reported observing the speed limit all the time, 62.0% said they use safety belts all the time, while of those who said they never observe the speed limit 54.9% said they use safety belts all the time (Chi Square = 31.56, pc.001) 3. O f those who reported observing the speed limit all the time, 81.6% said they never drink and drive, while of those who said they never observe the speed limit 65.5% said they never drink and drive (Chi Square =164.09, pc.001). 4. Of those who never drink and drive 44.3% felt that passive devices ( safety belts and air bags) are more important for safety than preventive devices (defined in the questionnaire as anti-lock braking systems) and 38.5% felt the opposite. In contrast of the few who reported they "always" drink and drive the corresponding percentages were 30.8 and 57.7 (Chi

5 Square = 24.94, p=.015). 5. O f those who never drink and drive 62.9% said they would be willing to pay more for airbags, whereas o f those who drank and drove all the time only 33.3% said they would (Chi Square = 8.58, p=.072). 6. Of those who never drink and drive, 17.8% thought that air bags can cause serious injury when they inflate, and 49.5% thought they could not, whereas of those who drink and drive all the time none thought they can cause serious injury and 81.8% thought they could not (Chi square = 27.66, p=.001). Trends in traffic safety related behaviors Statistically significant changes between years in safety behaviors were obtained for all three SI measures: use of safety belts, avoiding drinking and driving, and observing the speed limit. However, a consistent improvement was obtained only in the first two measures. The greatest change was in the use of safety belts, with the percent reporting they use safety belts all the time increasing from 41.5% in 1985 to 72.4% in 1992 (Chi Square =374.10, pc.001), i.e., a relative increase of nearly 75% (74.5% ). a less dramatic decrease in drinking and driving was obtained across the eight years with the percent reporting they never drink and drive increasing from 71.1% in 1985 to 78.0% in 1992 (Chi Square = 47.84, p=.002). One likely reason for the much smaller relative change (9.7%) is the initial higher level of compliance with refraining from drinking and driving vs using safety belts. A ssociations between health-related m easures and traffic safety related m easures There were many significant associations between tendencies to practice health-related behaviors and the three principal traffic safety-related behaviors. With respect to drinking and driving the findings were: 1. The percent who said they never drink and drive was inversely related to the rate of testing cholesterol: beginning with 83.2% of those who said they tested their cholesterol every 6 m onths or m ore often, and ending with 71.6% of those who said they had never tested their cholesterol (Chi square = 96.62, p<.001). The percent who said they did not drink and drive at all decreased from 79.2% of those who measured their blood pressure more often than once a year, to 68-70% of those who measured it bi-annually or less (Chi Square=92.48, p<.001). The am ount o f drinking people did "on a day when you drink" was associated as follows with each of the three safe driving behaviors: 1. Use of safety belts. The less the reported amount people drank, the more likely they were to use their safety belts "all the time" (Contingency coefficient =.20). Of those who limited themselves to 1-2 drinks in "a day when you drink", 67.0% reported using safety belts

6 (when sitting in the front seat) all the time; whereas o f those who said they typically have three or more drinks, only 49.8% reported using safety belts (when sitting in the front seat) all the time (Chi Square = , p<.001). 2. Observing the speed limit. The less the reported amount people drank, the more likely they were to observe the speed limit "all the time" (Contingency coefficient =.11). O f the drivers who said they limited themselves to 1-2 drinks, 47.3% reported observing the speed limit all the time; whereas of those who said they typically have three or more drinks, only 40.1% reported observing the speed limit all the time (Chi Square = 63.62, p<.001). 3. Drinking and driving. The less the amount people said they drank, the less likely they were to say they drink and drive (Contingency coefficient =.24). As can be seen from Figure 2, of those who said they limited themselves to 1-2 drinks in "a day when you drink", 71.9% reported they never drink and drive; whereas of those who said they typically have three or more drinks, only 52.1% reported they never drink and drive (Chi Square = , pc.001). A similar associations were obtained between frequency of drinking and observing the speed limit and drinking and driving (but not with the use of safety belts). Figure 2 : the Association between the Health Index (HI) and the traffic S a fety Index (SI) J P W K Percent who drink and drive relative bo the typical number of drinks i X UJ a CJ 3 V W c JC so BQ 40- R X * 20 1 Drink 2 Drlnki 1 Drfcito 4 Drinks Numt>Br <jp DrEnfcs Tyjjlnalty OjesemBd 6* Drinks

7 The multiple - though low associations between the different component measures, suggest that there may be underlying 'general' factors that determine a person's orientation towards health and traffic safety. Several statistical approaches were used to test this basic hypothesis, and they are described below. Calculation of Cronbach's Alpha for the component measures o f each index yielded alpha =.41 for the six measures contributing to the HI, and Alpha =.20 for the three measures o f the SI. This difference shows that the commonality that underlies the HI measures is much higher than that of the SI measures. Consequently, people are more likely to change one SI component behavior without much carry-over to other SI component behaviors than they are in the case o f HI component behaviors. The Pearson r correlation between the two combined measures was relatively low (though statistically significant at p<.001): r=.18. statistically, this means that less than 4% of the SI score can be accounted for by the HI score, and vice versa. From a more practical perspective, it means that people generally do not associate the two issues, and their safe or unsafe behavior behind the wheel is essentially unrelated to their health-related habits. Trends in HI and SI Perhaps the most interesting to note is the trend in the SI and HI measures over the 8-year data collection period. That trend is represented in Figure 3, which illustrates the changes in the average HI and SI (adjusted to a common scale of 1-100). Based on these trends: 1. Americans have only marginally - if at all - improved their health habits. Across the eight years the average HI score was 76.4 (s.d.=18.7), and the total change in mean HI from 1985 to 1992 was from 76.2 to 76.8; i.e., a relative increase of only one percent. Based on an analysis of variance conducted on the mean HI scores, this minimal change is not statistically significant [F(6,8363)=0.61]. In terms of the percent of people adhering to all HI component behaviors the change was from 17.0% to 19.0%; i.e., a relative increase o f 12%

8 POPULATION TRENDS IN HI AND SI: Avgragg HI and SI Scarps w - r S a 55 <p ao- BD- Legend Ar8M a HI AM M gk SI IB 5D- 1W5 I IBM l 1W? I S Y «r IBRD I I 8*1 i n s 2.Americans have improved their driving safety habits significantly from an average SI score of 59.9 in 1985 to an average SI score 71.4 in 1992; i.e. a relative improvement o f 19. This change was also statistically highly significant [F(6,6326)=20.12, pc.001]. Also, the percent of respondents who maintain all SI behaviors increased from 16.1% to 25.4%; i.e., a relative improvement o f 58%! 3. Although improvement in SI was monotonic - with every year yielding the same or higher SI than the previous year, the rate of improvement in the SI was not constant. Improvements in the SI were greatest from 1985 to 1986 (when the mean SI rose from 59.9 to 65.2, and complete adherence rose from 16.1% to 22.3%) and from 1987 to 1988 (when mean SI rose from 65.6 to 68.1, and complete adherence rose from 22.7% to 24.9%). C O N C L U SIO N S 1. The Safety Index indicates that over an eight year period ( ) the U.S. driving population has improved their driving safety habits quite markedly. This has been most pronounced in the use o f safety belts and not driving after drinking. 2. There were significant differences in safety behaviors as a function of age, with the percentage who practice all safety behaviors tending to increase with increasing age

9 Refraining from drinking and driving was relatively constant until the age of 40, beyond which there was a gradual improvement with age, so much so that of those who were 65 years old or older, 90% reported they never drink and drive. 3. Unlike the SI index, no significant parallel improvement in the Health Index was obtained during the 8-year period, and there was a very low correlation between the two sets of behaviors as reflected in the HI and SI (r=.18) 4. It is not easy to separate general drinking behavior from drinking and driving. The more frequently people drink, and the more they drink when they do drink, the more likely they are to drink and drive. R E F E R E N C E S Department of Transport, United Kingdom (1991). The Older Road User: measures for reducing the number of casualties among older people on our roads. Evans, L. (1991) Traffic Safety and the Driver. Van Nostrand Reinhold, New York. Louis Harris And Associates. (1993) Survey Methodology of 1993 Prevention Index. Shinar, D. (1993). Demographic and socioeconomic correlates of safety belt use. Accident Analysis and Prevention