Pergamon Accid. Anal. and Prev.. Vol. 26, No. 3. pp. 287-295, 1994

Copyright 0 1994 Elsevier Science Ltd Printed in the USA. All rights reserved

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THE EFFECT OF ADULT BELT LAWS AND OTHER

FACTORS ON RESTRAINT USE FOR CHILDREN UNDER AGE 11

JULIE RUSSELL, MARCIE-JO KRESNOW, and ROBERT BRACKBILL

Centers for Disease Control, Atlanta, GA, U.S.A.

(Received 13 October 92; in revised form 17 March 1993)

Abstract-We used data from 11 states (5,449 respondents) to examine the association between self-reported consistent use of occupant restraints for children under 11 years of age and presence of adult belt-use laws while controlling for other factors. Self-reported safety belt use by adults, age of youngest child in the household (child restraint use decreased with increasing age), and adult educational attainment were significant predictors of child restraint use; respondent age, raceiethnicity, sex, marital status, household income, and employment status were not. Adult and child occupant restraint use was higher in states with an adult safety belt law than in states without such a law.

Keywords-Child restraints, Child safety seats, Injury control, Occupant restraints, Prevention

INTRODUCTION

In the United States motor vehicle crashes are the leading cause of death among children between I and 18 years of age. The likelihood of a pediatric injury due to a motor vehicle crash can be greatly reduced by the use of occupant restraints (Chorba and Klein 1992; Agran, Castillo, and Winn 1990; Partyka 1988; Kahane 1986). Between 1977 and 1985, all 50 states passed legislation requiring the use of child safety seats or safety belts. However, the requirements of these laws vary among the states with regard to the child’s age, weight, and occupant position in the vehicle. Child restraint laws are esti- mated to reduce injuries to young children by 8%-59% (Guerin and MacKinnon 1985; Hall et al. 1983; Williams and Wells 1981). Despite the passage of these laws and subsequent reductions in injuries, motor vehicle crash-related injuries continue to be a major source of disability or death for children in the United States (NHTSA 1991a; CDC 1990; Agran et al. 1990; Runyan et al. 1985). Data from the Na- tional Highway Traffic Safety Administration (NHTSA), which are based on observational sur- veys from 19 cities, indicate that occupant restraint use decreases with increasing child age. Restraint use is estimated to be 83% for infants, 84% for tod- dlers (aged 1-4 years), and 57% for children aged 5- 11 years, and 29% for teenagers (NHTSA 1991 b).

Earlier studies have described the relationship

between child restraint use and other factors. In Maryland in 1981, Gielen et al. (1984) conducted a statewide telephone survey of parents with children under age 5 to identify factors that differentiate child safety seat users from nonusers. Factors related to use of child safety seats were: attitude towards car seat (child discomfort, child resistance, unneces- sary, expensive, inconvenient); age of youngest child; parental safety belt use; parental use of ciga- rettes; family size; and income.

Numerous other studies have been conducted showing a positive relationship between parents’ own use of occupant restraints and their use of re- straints for their children (Wagenaar, Molnar, and Margolis 1988; Gielen et al. 1984; Hletko et al. 1983; Hoadly, Macrina, and Peterson 1981; Neumann et al. 1974), between higher adult educational attain- ment and other indicators of higher socioeconomic status and child restraint use (Wagenaar et al. 1988; Gielen et al. 1984; Hletko et al. 1983; Pless and Roughmann 1978; Neumann et al. 1974), and higher rate of use of occupant restraints for children among married adults than unmarried adults (Wagenaar et al. 1988; Hletko et al. 1983; Neumann et al. 1974). There were several studies that showed a positive relationship between white race and use of occupant protection for children (Wagenaar, et al. 1988; Gie- len et al. 1984; and Neumann et al. 1974). Two stud- ies found a negative association between family size and use of occupant protection for children (Geilen et al. 1984; Neumann et al. 1974). An inverse rela-

287

288 J. RUSSELL et al.

tionship was also observed between the age of the child and the use of occupant restraints (Wagenaar et al. 1988; Gielen et al. 1984; Pless and Roughmann 1978; Neumann et al. 1974).

Adult safety belt use is positively associated with child restraint use, and self-reported adult safety belt use increases by 28 to 45 percentage points when a state law mandating adult restraint use exists (Escobedo et al. 1992). Therefore, adult safety belt laws should potentially impact child re- straint use, although to our knowledge this effect has not been directly assessed.

We examined the association between self-re- ported consistent use of occupant restraints for chil- dren IO years of age or younger and a number of factors, some not previously studied (adult safety belt law; adult safety belt use; age of youngest child under age 11; respondent’s age, race, or ethnicity; sex; educational attainment; marital status; employ- ment status; and household income). We wanted to identify factors related to child restraint use (child safety seats or safety belts) that can be used to target intervention programs to increase restraint use for children 10 years of age and younger.

METHODS

Data were collected through population-based, random, digit-dialed telephone surveys originally conducted by state health departments as part of the Centers for Disease Control’s (CDC’s) Behavioral Risk Factor Surveillance System (BRFSS). Com- plete details have been published previously (Rem- ington et al. 1988; Gentry et al. 1985). Briefly, re- spondent households were selected through a probability cluster sampling method (three-stage Waksberg Random Digit Dialing) to select telephone numbers (Waksberg 1978). Trained interviewers ad- ministered the Behavioral Risk Factor (BRF) Ques- tionnaire to one randomly selected adult 18 years or older in each selected household. Information was collected on demographics and high-risk health behaviors such as nonuse of safety belts and drinking and driving.

Our analysis was restricted to respondents in the 11 states that elected, in 1988 or 1989, to adminis- ter a standard Injury Control and Child Safety Mod- ule (ICCSM) developed by CDC. As part of the ICCSM, only respondents whose youngest child was 10 years old or younger were asked to specify the child’s age and to report the frequency of restraint use for that child. Other questions on the ICCSM addressed behaviors related to fires, scalds, and poisonings.

The states’ survey samples were roughly equal in size. To account for population differences in each

state, we adjusted the data to reflect each respon- dent’s probability of selection as well as the age, sex, and race/ethni~ity distribution of the state census estimate. For three states surveyed in 1988 and 1989, weights were divided in half. The resulting weight may be interpreted as the number of population members whom the respondent represents as a member of the sample.

All states surveyed had child restraint laws dur- ing 1988 and 1989. However, six states (Arizona, Maine, Kentucky, Nebraska, Rhode Island, and West Virginia) had no adult safety belt law during that time; four states (Idaho, Maryland, Pennsylva- nia, and Washington) had a secondary enforcement mandatory safety belt law (a vehicle must be stopped for a traffic violation before a citation for nonuse of safety belts could be issued); and one state (New York) had a primary-enforcement mandatory safety belt law (vehicles could be stopped for a safety belt law violation alone). Nine states’ child passenger protection laws covered all children under 5 years of age, but others used both age and size of the child as the criteria for mandatory restraint use.

Data were available for 20,905 respondents to the BRF questionnaire in the I I states. Of these, 5,449 (26%) had a youngest child under 1 I in their households. Data were separated into two sub- groups of states: (i) those in which a state law re- quired adult belt use (law states-includes primary and secondary), and (ii) those without such a law (no-law states). The number of respondents for each subgroup was nearly equal (2,699 for no-law states and 2,750 for law states). Law states were largely urban with the exception of Idaho, and no-law states were mainly rural with the exception of Rhode Island and Arizona. We defined a state as rural if, according to the U.S. Bureau of Census, more than 35% of the population lived in a rural area (U.S. Congress, Office of Technology Assessment 1990).

All analyses were done by using SUDAAN (Survey DAta ANalysis) software to account for the complex design of these surveys* (Shah et al. 1991). For all data presented, point estimates and confidence intervals were based on weighted data. Statistical significance was determined using a p value of c.05.

We used two categories of child restraint and

*In preliminary analyses, we examined the design effect of each covariate to determine if an analysis that accounted for the complex survey design was necessary. The design effect is the ratio of the sampling variance that reflects the complexities of the design with the sampling variance assuming a simple random sample of the same size. Our results suggested that failure to include sample design parameters in the analysis would result in standard errors that were too small (an excessive number of sigr’ficant findings). The design effect for the outcome, child restraint use, was 2.47.

Restraint use for children under age 11 289

Table 1. Distribution of characteristics of adult respondents* in the 1 I states combined and in law states and no-law states (11 selected states: United States, 1988-1989)

Self-reported characteristics

(N = 5449) All states

% (n)

(N = 2750) Law states

% (n)

(N = 2699) No-law states

% (n)

Child restraint use Always Almost always Sometimes Rarely Never

Adult belt use Always Almost always Sometimes Rarely Never

Age of youngest child O-l years 2-3 years 4-5 years 6-10 years

Adult age 18-24 years 25-34 years 35-44 years 45+ years

Race/ethnicity White/white hispanic Other

Sex of respondent Male Female

Level of education < High school (HS) HS/Technical school > High school

Marital status Married/couple Divorced/separated/widowed Never married

Household income < $20,000

$20,000-$50,000 > $50,000

Employment status Employed Homemaker Student Retired Unemployed

79.4 (4273) 81.1 9.5 (529) 9.3 5.3 (281) 4.8 2.8 (141) 2.3 3.1 (152) 2.5

(2202) 74.3

(280) 10.1

(115) 6.6

(48) 4.1

(51) 4.9

54.8 (2761) 17.6 (917) 12.8 (728) 6.5 (438) 8.3 (573)

58.7 (1612) 18.5 (534) 11.2 (276) 5.1 (146) 6.6 (156)

25.1 (1222) 26.3 23.8 (1274) 23.5 17.4 (995) 16.8 33.7 (1958) 33.4

(651) 21.6

(637) 25.0

(485) 19.0

(977) 34.5

11.4 (528) 11.0 (271) 48.0 (2748) 47.3 (1336) 31.7 (1787) 32.5 (934)

8.9 (386) 9.2 (209)

83.6 (4880) 80.5 16.4 (567) 19.5

(2310) 92.9

(439) 7.1

45.9 (2154) 46.2 54.1 (3295) 53.8

(1082) 44.9 (1668) 55.1

11.5 (603) 10.9 41.9 (2277) 41.1 46.6 (2564) 48.0

(266) 13.3 (1083) 44.3 (1398) 42.3

80.2 (43 12) 10.7 (770) 9.1 (364)

79.1 (2128) 11.2 (416) 9.7 (205)

25.4 (1470) 23.2 57.5 (2697) 57.3 17.0 (686) 19.4

(663) (1379)

(432)

72.4 (3899) 73.6 18.0 (1087) 17.2 2.4 (123) 2.2 1.5 (54) 1.3 5.7 (274) 5.8

(2006) 69.1

(507) 20.6

(62) 3.1

(25) 1.8

(147) 5.4

(207 I ) (24% (166)

(93) (101)

43.2 (1149) 15.2 (383) 17.5 (452) 10.8 (292) 13.4 (417)

(571) (637) (510) (981)

12.5 (257) 50. I (1412) 29.4 (853)

8.1 (177)

(2570) (128)

(1072) (1627)

(337) (1194) (1166)

83.3 (2184) 9.1 (354) 7.5 (159)

32.0 (807) 58.1 (1318)

9.9 (254)

(1893)

(580) (61) (29)

(127)

*Refers to 5,449 adult respondents with a child under age 11 in their household. tLess than 1% of data are missing except for the income variable which has 11% missing data.

adult belt use: (i) consistent users (always buckle up) and (ii) inconsistent users (almost always, some- times, rarely, or never buckle up). Prevalence rates were computed to examine the association between consistent child-restraint use and other variables re- ported. We assessed the significance ofeach associa- tion (crude) using the Pearson chi-square test statis- tic (Feinberg 1977). This is analogous to the same test statistic for nonsurvey data (Shah et al. 1991).

Logistic regression modelling was used to ex- amine the association between consistent child re-

straint use and the variables of interest. The strength of the association was assessed by using the odds ratio (OR). We calculated 95% confidence intervals (CIs) around each OR to indicate the precision of these estimates.

Correlation among independent variables in the full logistic regression model can greatly distort the estimated ORs (Neter, Wasserman, and Kutner 1983). Consequently, we did not include adult safety-belt use in a model with demographic charac- teristics because previous studies show these vari-

290 J. RUSSELL et al.

Table 2. Prevalence of child restraint use by characteristics of adult respondents* in law states and no-law states (1 I states: United States, 1988-1989)

Self-reported characteristics

Law states No-law states

(Standard (Standard 9 error %) % error %)

Adult belt use+ Always Almost always Sometimes Rarely Never

Age of youngest childt O-l years 2-3 years 4-5 years 6-10 years

Adult age+ 18-24 years 25-34 years 35-44 years 45+ years

Raceiethnicity White/white Hispanic Other

Sex of respondent Male Female

Level of education? < High School (HS) HSiTechnical School > High School

Marital statusS Married/couple Divorced/separatedlwido.wed Never married

Employment status Employed Homemaker Student Retired Unemployed

92.9 (1.0) 92.7 (1.0) 76.1 (2.6) 71.1 (2.9) 59.8 (4.0) 59.8 (2.8) 57.3 (5.5) so.2 (3.8) 51.3 (5.7) 57.4 (3.2)

91.6 (2.2) 95.8 (1.0) 87.6 (1.8) 83.6 (1.8) 79.2 (2.7) 71.1 (2.7) 69.5 (2.0) 56.2 (2.0)

72.2 (4.6) 82.9 (3.2) 85.7 (1.4) 78.2 (1.4) 79.8 (1.7) 66.5 (2.1) 72.6 (4.5) 66.2 (4.4)

81.8 78.3

(1.1) (3.2)

74.4 73.4

(1.1) (4.5)

80.9 (1.7) 74.5 (1.7) 81.3 (1.4) 74.2 (l-4)

73.7 (4.4) 62.5 (3.4) 78.2 (1.7) 73.6 (1.6) 85.3 (1.5) 78.8 (1.5)

83.2 (1.1) 74.5 (1.2) 77.1 (3.1) 73.1 (2.9) 68.7 (5.1) 74.0 (5.0)

81.8 (1.3) 74.5 (1.2) 82.2 (2.2) 76.7 (2.2) 67.7 (9.9) 75.8 (8.6) 74.3 (13.0) 71.5 [ 10.7) 76.4 (6.2) 61.9 (6.0)

*Refers to 5,449 adult respondents with a child under age I I in their household. +Significant association between child restraint use and the characteristic in both

law and no law states (chi-square test p < 0.05). *Significant association between child restraint use and marital status in law states

(chi-square test p < 0.05).

ables are associated (Hunter, Stewart, and Rodgman 1988, 1990; Lund 1986). Of the three variables indi- cating socioeconomic status, only educational at- tainment was considered for modeling. Household income was omitted because of the large number of missing values (11.6%) and because the income lev- els vary from state to state. Employment, a nonsig- nificant predictor in univariate analysis, was also dropped.

The significance of each variable in the model and the interaction of each variable with adult safety- belt law were assessed using the Satterthwaite F-

statistic with correction for numerator degrees of freedom (B. V. Shah, personal communication, May 1991).

RESULTS

In general, the distribution of characteristics (Table 1) for all states was very similar to that of the law states. Compared with no-law states, a higher percentage of respondents in law states classified themselves into the “other” raceiethnicity category (19.5% versus 7.1%), had more than a high school education (48.0% versus 42.3%), had a household income greater than $50,000 (19.4% versus 9.9%), and reported consistent adult safety-belt use (58.7% versus 43.2%). Consistent use of child restraints was high in both subgroups (81.1% in law states and 74.3% in no-law states).

In both law and no-law states, consistent child restraint use was significantly associated with adult

Restraint use for children under age 11 291

80 -

60 -

50 -

40 -

30 -

20 -

10 -

l *, Inconsistent Adult Safety Belt Users

0; , , , , , , , , , , 0 12 3 4 5 6 7 8 910

Age of Youngest Child (Years)

Fig. 1. Prevalence of consistent occupant restraint use for children by child age and adult safety belt use (11 states: United States 1988-1989).

age, higher educational attainment, younger child age, and consistent adult belt use (Pearson chi- square test); however, the association with marital status was significant only in law states (Table 2).

Both consistent and inconsistent adult belt us- ers reported high rates of restraint use for children aged 1 year or younger (Fig. 1). Consistent adult belt users reported high rates of restraint use for their children regardless of their ages (95.5% for l- year-olds to 84.7% for IO-year-olds), but inconsis- tent adult belt users had sharply lower rates of re- straint use for older children (93.1% for I-year-olds to 28.8% for IO-year-olds).

Child restraint use in law states generally ex- ceeded that in no-law states (Fig. 2). However, 95% CIs overlapped at each level of child age (law versus no-law) except for ages 9 and 10. In no-law states, consistent child-restraint use decreased sharply from ages 1 through 10, but in law states the decrease was less pronounced. Occupant restraint use for 9- and IO-year olds was similar to that of adults. Within law and no-law states, 95% CIs around prevalence estimates for 9- and IO-year-old children overlapped those for adults.

Using logistic regression modeling, we assessed

the relationship between the outcome variable, child restraint use, and each variable unadjusted for any other variable (crude OR). Adult safety belt law, adult age, marital status of respondent, higher edu- cational attainment, consistent adult belt use, and younger child age were identified as significant pre- dictors of the outcome (not shown).

To further assess the relationship between adult safety-belt law and child restraint use, we computed the ORs and 95% CIs for adult safety belt law in three models (Table 3). In Model 1, adult safety belt law, unadjusted for other variables, was a significant predictor of child restraint use (OR = 1.48). Even when adjusted for demographic variables (Model 2), the existence of an adult safety belt law was still a significant predictor of child restraint use, as was adult age, marital status of respondent, and higher educational attainment (Satterthwaite F-test, p < 0.05). Our final model included all variables in Model 2 plus child age and a term representing the interac- tion (joint effect) of an adult safety belt law and child age. Because the interaction term was significant, ORs for adult belt law in Model 3 are presented by level of child age. With the addition of these new terms, higher educational attainment was still sig- nificantly predictive of child restraint use.

292 J. RUSSELL et al.

90

80

Child Restraint Use. Law States

Adult Safe

3 Belt Use

Law tates

Child Restraint Use. No Law States

Adult Safety Belt Use, No Law States

20

IO

i 00

012345678910 Age of Youngest Child (Years)

Fig. 2. Prevalence of consistent adult safety belt use and child restraint use by child age in law and no-law states (I 1 states: United States 1988-1989).

DISCUSSION

If adult-reported child restraint use is accurate, then restraints are not being used for at least 25% of children younger than 11 years. Child restraint laws in more than two-thirds of the states do not cover children over the age of 5. Although the safety belt laws of some states do cover children over age 5, there are still groups of children not covered by either law (Teret 1986.) State chiId restraint laws need to be expanded to ensure that all child occu- pants are restrained. To develop effective preven- tion programs, we need to know more about the parents of children who are still not restrained de- spite existing child restraint laws. Results of this study corroborated others indicating that adults who do not use safety belts themselves are less likely to use restraints for their children (Margolis, Wagen- aar, and Molnar 1992; Wagenaar et al. 1988; Gielen et al. 1984; Hletko et al. 1983; Hoadly et al. 1981; Neumann et al. 1974). Because nonbelted adults are more likely to be in a crash and to exhibit other risk-taking behaviors, children traveling with these adults may be at greater risk of a motor vehicle injury (Hunter et al. 1988; CDC 1991b).

Our study, like others, showed that occupant

restraint use was inversely related to child age (Mar- golis et al. 1992; Wagenaar et al. 1988; Gielen et al. 1984; Pless and Roughmann 1978; Neumann et al. 1974). The effect of increasing child age on decreas- ing child restraint use was strong but was mitigated if the adult was a consistent belt user (Fig. 1) or if an adult belt use law existed (Fig. 2). Higher adult educational attainment was the only demographic variable significantly associated with increased re- straint use for children. This variable has also been shown to be associated with adult belt use (Lund 1986). More programs are needed to reach parents of low educational attainment. Because low educa- tional attainment is often associated with low socio- economic status, these parents may be reached through hospitals that serve low income communi- ties or through federal programs, such as Head Start, directed at parents with young children.

Efforts must continue to increase safety belt use among adults and, consequently, among children. Focusing on children younger than 11 years is im- portant, because restraint use for this group could be increased by in~uencing the children directly or by influencing their parents. Increasing belt use among children now has the potential for increasing use among teenagers in future years (Sleet, Hollen-

Restraint use for children under age I1 293

Table 3. Association between child restraint use and adult safety belt law adjusted for selected respondent* characteristics (11

States: United States, 1988-1989)

Model

95% Odds Confidence ratiot interval

Model 1 Presence of an adult safety belt

IawS Model 2

1.48 (1.24-1.77)

Presence of an adult safety belt law*, sex, race/ethnicity, adult

age*, marital status*, educational attainment*

Model 3 1.53 (1.28-1.83)

Presence of an adult safety belt law, sex, race/ethnicity, adult age, mar- ital status, educational attain- ment*, child age, and child age- adult law interaction*

Child age O-l years 0.50 (0.24-1.04) 2-3 iears 4-5 years 6- 10 years

1.37 (0.89-2.09) 1.59 (1.05-2.40) 1.82 (1.41-2.35)

*Refers to 5,449 adult respondents with a child under age 11 in their household. Eight respondents were excluded from Models 2 and 3 because of missing values (5 missing educational attainment, 3 missing marital status).

+Odds ratios are-for adult safety belt law and were calculated using the logistic regression procedure in SUDAAN. The referent group is composed-of respondents in states with no adult safety belt law. For Model 3 ORs are presented by level of child age.

$Significant predictor of child restraint use (Satterthwaite F-statistic, p < 0.05).

bath, and Hovel1 1986). Teenagers currently show the lowest belt use of any age group and are the drivers at highest risk of all age groups (NHTSA 1991b; CDC 1991a; CDC 1992). Our results, based on a large representative sample, offer a new per- spective regarding predictors of child restraint use. Multivariable statistical analysis showed that many of the factors previously considered to be related to child restraint use (respondent age, race/ethnicity, sex, marital status) were not statistically significant in the presence of other factors.

Because these data are cross-sectional and not longitudinal, we cannot be sure that the relationship between child age and child restraint use will be the same in future years for children who are preschool age now. For example, children who were school age (other than 5 years) in 1988 and 1989 were not as likely to have ridden in child safety seats when they were infants or preschoolers because not all states had child restraint laws. Perhaps children who start out riding in child safety seats as infants will be more likely to be restrained as older children. This issue can be addressed in later years by using BRFSS data.

Possible limitations of this analysis include the following: (i) results based on data from only 11 states cannot be generalized to the entire United States; (ii) telephone surveys underrepresent popu- lations of lower socioeconomic status because they are less likely to own telephones or to respond to surveys (Smith and Remington 1989); (iii) no data were available to indicate if the adult respondent was the child’s parent-Margolis et al. (1992) found that parents were three times more likely to use a child restraint than other adults; (iv) no data were collected on the adults’ knowledge of child restraint laws in their state, a variable shown to be associated with child restraint use (Wagenaar et al. 1988); (v) the child restraint laws of each state were different, and while in some states the child restraint law over- lapped with the safety belt law so all children were covered (e.g. New York), in the other states in this study child restraint and safety belt laws omitted restraint requirements for older children (Insurance Institute for Highway Safety 1992); (vi) the lack of information on family size and child occupant seat- ing position prevented us from assessing these im- portant aspects of child restraint use; (vii) the degree of overreporting of child restraint use is unknown, a factor that is further complicated by the ov&-re- porting of adult safety belt use, one of its significant predictors.

Recent studies have shown that self-reported adult safety belt use is overreported by a factor of 1.2 to 2 when compared with observed safety belt use (Streff and Wagenaar 1989). Hunter et al. (1988) compared observed belt use with self-reported safety belt use for the same people in North Caro- lina, a state having a primary enforcement safety belt law in place since 1985. Of those who reported always wearing a belt, 87% were observed to be belted, and of those who reported wearing a belt most of the time, 48% were observed to be belted. Adults in law states may overreport safety belt use more than those in no-law states because using a safety belt may be perceived as a more socially desir- able response. The issue of the validity of adult- reported child restraint use has not been adequately studied (Webb, Sanson-Fisher, and Bowman 1988; Stulginskas, Verreault, and Pless 1985).

We also had analytic difficulties using these data. Adults in rural states are less likely to wear a safety belt than those in urban states (Baker, Whit- field, and O’Neill 1987). Law states in our study were predominately urban, while no-law states were predominantly rural. In addition, there were no data collected allowing us to identify individual respon- dents living in rural or urban areas within a state. Therefore, we were not able to separate out these

294 J. RUSSELL et al

two issues in the analysis. We could not analyze adult safety belt use and demographic variables to- gether because results of numerous studies show that these variables are associated. Demographic variables are overwhelmed when adult safety belt use is included in the mode1 (Margolis et al. 1992). This correlation prohibited us from obtaining valid estimates for the relationship between adult belt use and child restraint use while adjusting for demo- graphic variables.

Despite these limitations the BRFSS is a valu- able tool for monitoring safety belt use in the genera1 population and provides an additional measure of the relationship between adult and child restraint use in the United States.

Ackno~,led~emenfs-The authors acknowledge Delinda Gibson for her computer programming support and Joann O’Neil for her support in running the SUDAAN software. We also extend our thanks to Marilyn Kirk for graphics support, Melissa McCraven for secretarial support, and our colleagues at CDC who reviewed numerous drafts of the paper.

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