Overview

We used the Safe Communities model in an ethnically diverse population in the southeast part of Dallas, Texas, in order to increase child restraint use among children 0–8 years of age, in motor vehicles in that population. In this model, members of the target community are involved in the design and decision-making of injury prevention programmes.10 The intervention involved a multifaceted, community-based, culturally integrated programme, similar to a strategy that had been successfully developed and implemented in another geographic area of Dallas a few years earlier.12 We focused our efforts on increasing compliance with Texas state child restraint law, which required children under 4 years old to ride in a child safety seat, and children 4–16 years old to ride either in a child safety seat or a seat belt; we also emphasised the added protection for children 5–8 years old to ride in a booster seat. Collection of observational data of child restraint usage in the target area and in a comparison area where no intervention took place allowed us to use this quasi-experimental observational design to evaluate the research problem: whether the Safe Communities approach resulted in increased child restraint usage.

Setting

The target population included three zip codes in southeast Dallas County, with a population in the 2000 census of 176 656, including 29% black, 36% Hispanic, 32% white and 3% other; 19% were children less than 10 years of age. A comparison population in the far southwest part of Dallas County, where no formal intervention was performed, included five contiguous zip codes with a population of 132 734, with 21% black, 26% Hispanic, 48% white and 6% other; 17.2% were children less than 10 years of age (table 1).

Programme interventions

The Safe Communities model involved a multifaceted approach consisting of assessing the community, getting input from community members about issues and views regarding injury prevention and seat belt use, designing the intervention, and then evaluating its impact. A series of focus groups among various ethnic groups helped to determine the location and times of CSS classes and important additional content for the classes. Included in the assessment were several community groups and agencies in the area, including business leaders, churches, schools, day care centres, Camp Fire, Salvation Army and Social Services, as well as the staff of two local paediatric clinics. The various groups helped to recruit young parents to attend CSS classes and to publicise the activity. A detailed review of the process involved in setting up the interventions can be found in appendix 1, available online at the following website: http://www.injurypreventioncenter.org/pdf/Community%20Program%20Intervention%20SE%20Dallas%20TX%202002-2005.pdf.

The staff of the Injury Prevention Center of Greater Dallas supervised the project; the Injury Prevention Center is housed within the Parkland Health & Hospitals System. The assessment phase began on 1 October 2002, the pre-intervention observations took place from January to June 2003, and the post-intervention observations took place from January to June 2005. The interventions took place from January 2003 through June 2005.

The interventions in the target community included a multidimensional awareness programme about the importance of children riding in CSSs and booster seats and the applicable state laws, and ongoing classes at various locations and times, where parents could receive instruction about CSS usage and receive a CSS or booster seat if they needed one (see link to appendix 1 above). A ten dollar donation was requested, but no one was refused a seat if they were unable to afford it.

There were three main areas of emphasis in the CSS classes: (1) children riding restrained in CSSs, booster seats or seat belts, depending on age; (2) drivers wearing a seat belt, both for the driver's protection and as a good example for the child; and (3) children riding in the back seat of the vehicle, which is safer in crashes. CSS classes were held at the community clinic, day care centres, grade schools and occasionally at churches, apartment complexes and neighbourhood recreation centres. In addition, multiple free ‘car seat checks’ were held at community locations including schools, day care centres, grocery stores and police stations, where CSS technicians checked CSSs for proper installation and gave out CSSs if the family did not have a proper one in the vehicle at the time. No interventions took place in the comparison area.

Data collection

A series of observational surveys of child and driver restraint use were conducted in several sites in the target area and the comparison area during January–June 2003 and January–June 2005. The purpose of these surveys was to collect data regarding the prevalence of restraint use over time and to determine whether there was an increase that could be attributable to the programme. Observers were trained in the use of a standardised observation survey form that had been modified slightly from one used by the Texas Transportation Institute for the past 20 years for longitudinal studies of restraint use throughout Texas.13 Before beginning the formal observations, duplicate observations were performed by two observers during training sessions to ensure consistency of observations and coding. Surveys were conducted as vehicles entered parking lots at three types of selected locations in the target and comparison areas: grocery stores, day care centres and elementary schools. In this setting, vehicles typically were travelling at approximately 8 km/h. All vehicles that were observed during a pre-set 1 hour period of time and that carried at least one passenger estimated to be 0–8 years of age were included in the sample. Observers noted the use of CSSs, booster seats or seat belts among child passengers, the use of seat belts among drivers, the child's location within the vehicle (ie, front or back seat), the type of vehicle, and an estimate of the age, gender and race/ethnicity of all child passengers. Race/ethnicity was estimated by the observer, and categorised as black, white, Hispanic, other or unknown. This variable was included in order to estimate whether the impact of the programme varied by race/ethnicity, and, if it did, to attempt to control for differences in the multivariate analysis.

Data management/analysis

Initially, a univariate analysis was performed to measure the association of several variables on the odds of a child being properly restrained (compliant with state law), irrespective of the time frame. Subsequently, variables that were found to be associated with child restraint use in this univariate analysis were incorporated into a multivariable model (see below). The impact of the programme was assessed based on analysis of outcome variables (child restraint use, driver seat belt use, and child location in the back seat) between the baseline period when the intervention started (January through June 2003) and the post-intervention period when the intervention ended (January through June 2005). The change for the outcome variables within the target area was compared with the change within the comparison area and tested for statistical significance using a multivariable statistical model. For these analyses, the unit of analysis was the child. A total of 9478 observations were included. For analyses, restraint use was defined as a child being restrained in compliance with Texas state law for the estimated age of the child. Texas state law during the period of this study required that children less than 4 years old be restrained in a child safety seat, and children between 4 and 16 years old had to be restrained, either in a child safety seat or a seat belt.14 Although the law also required children who were less than 36 inches tall to ride in a child safety seat even if they were older than 4 years, we made no attempt to measure child height in this survey.

Data were entered using Epi Info 6.2. Accuracy of data entry was checked by re-entering a 10% sample of records; the error rate was less than 1%. Data was exported to a Stata V.10.0 format for statistical analysis using the xtmelogit command for multilevel analysis.

We used a multilevel hierarchical model to estimate the effect of the programme. The model accounted for clustering of patient data within each of 34 sites with repeated measures over time, and for clustering of passengers within a vehicle. Specifically, we used the random intercept mixed-effects logistic regression model (Stata/SE 10.0, xtmelogit) with random effects for vehicle and site. The final model also included race, gender, age, seat location, driver belt status and vehicle type, all measured as fixed-effect covariates. p Values of <0.05 and ORs with 95% CIs that did not include 1.0 were considered significant. We also separately constructed two similar multilevel models to assess the change in the target area versus the comparison area for two other outcomes: driver seat belt use and children riding in the back seat of the vehicle. For these models, 265 (2.8%) records with missing data were excluded from analysis, leaving 9213 (97.2%) child observations. For driver seat belt use, the model would not converge with all of the variables included, so that model did not include the additional level of site, but did include other variables.

Additional data

Another means of monitoring child restraint use in the target area used data that had been collected by the Texas Transportation Institute (TTI) for observations of restraint use among preschool age children in Dallas that included one of the target zip codes (75 217) for 2003 and 2005 (the first and last years of the project). These observations have been performed in March of each year since 1984,13 and were carried out without knowledge of the interventions that were part of this project.