Operation Safe Crossing: Using science within a community intervention

Transcription

1 Operation Safe Crossing: Using science within a community intervention Voas, R.B.; Lange, J.; Tippetts, A.S.; Johnson, M. Pacific Institute for Research and Evaluation, Landover, MD, USA Corporate Drive, Suite 220, Landover, MD, 20785,USA Keywords: Underage drivers; binge drinking; community programs; national borders; DUI enforcement; injuries Abstract This paper describes the use of research data in managing and conducting a large drunk-driving enforcement program at the U.S./Mexican border to reduce the number of youths crossing the border to drink in Tijuana. Data from a border breath-test survey were used to dramatize the problem and gain public support for action. The data were also used to help design the enforcement effort and measure progress in reducing the cross-border drinking problem. Analysis of just less than 3 years of data involving more than 2 million pedestrians returning from Tijuana indicated that this effort reduced the number of late night crossers by 26%. Introduction With the founding of the drunk-driving advocacy movement by organizations such as Mothers Against Drunk Drivers (MADD) and Remove Intoxicated Drivers (RID) in 1980, legislative action on impaired driving grew from approximately 50 to 200 laws passed by the states each year over the next 5 years (NHTSA, 1998). Action on impaired driving legislation has remained at that level ever since. However, media coverage of the drunk-driving problem and arrests for impaired driving, after an initial increase in the mid-80s, have decreased (McCarthy, 1988). Although several factors account for the failure of enforcement and publicity to keep pace with legislation, it appears that activist organizations can have more immediate and broader influence at the state level than at the community level where most enforcement and public information programs must be generated. Recognizing that laws must be implemented at the community level, private and federal agencies have initiated community programs to organize local resources to promote federal and state drug and alcohol (AOD) legislation. Among these are the Center for Substance Abuse Prevention (CSAP) Community Partnerships, the Robert Wood Johnson Fighting Back program, the National Highway Traffic Safety Administration (NHTSA) Safe Communities program, and the National Institute on Alcohol Abuse and Alcoholism (NIAAA) Community Trials program.

2 The Community Trials program (Holder et al., 1997) provided an opportunity to explore the role of systematically collected data in supporting programs at the community level. Traditionally, the scientist has tended to be confined to the role of the program evaluator. In this role, emphasis is placed on a minimum of interference with the program itself. Measures should be made before and after the completion of the tested program. Measurements during program operations, if any, must be passive and must not affect those operations. The investigator must watch for data collection methods that might influence the project being evaluated. The Community Trials program reversed this process and made the investigator an integral part of the community program, using scientific information to design and implement countermeasures as well as measure program progress. This paper presents an initial evaluation of one element of a successor community program Operation Safe Crossing (OSC), which built upon the procedures developed in the Community Trials program. OSC added to the knowledge of how to combine systematic data collection with media advocacy procedures (Treno & Holder, 1996) to support both the organization of the community to deal with a public health problem and the development and implementation of countermeasures. The integration of data collection with media advocacy is designed to achieve two objectives: (1) enhance media coverage by providing interesting information that attracts the interest of local outlets, and (2) provide support for local police to increase resources devoted to enforcement. This paper attempts to measure the effect of this enhanced public information and increased enforcement on youthful high-risk drinkers. Materials and methods The Cross-Border Binging Problem Each Friday and Saturday night, between 4 and 7 thousand youths under aged 25 cross from San Diego, California, into Tijuana, Mexico, to take part in the nightlife where the legal drinking age is 18, rather than 21, and where alcohol is cheap and plentiful. Many are over the legal BAC limit when they return early the next morning to get into their vehicles on the U.S. side of the border and drive up to 90 miles to their homes. This high-risk drinking by young Americans in Tijuana had existed for the better part of the last century when, in 1992, the local media began to cover drinking by girls as young as aged 14 in Tijuana. This press interest motivated the San Diego County Department of Health Services to fund a pilot survey of youths returning late at night from Tijuana. That survey demonstrated that the cross-border binging phenomenon was not simply a rite of passage for a few underage males; but, with the population growth in San Diego, it was producing hundreds if not thousands of legally impaired drivers each weekend (Lange & Voas, 2000 in-press). Operation Safe Crossing Once San Diego s city and county officials became aware of the magnitude of the problem, an effort was undertaken to develop a program to reduce the number of impaired drivers returning from Tijuana following an evening of binge drinking. Organization of the effort was contracted to the Institute for Health Advocacy (IHA) in San Diego which went about the process of organizing a local consortium to develop and promote a countermeasure program (Baker, 1997). The principal initial effort of the organization established by IHA, OSC (which is the subject of this report), involved strengthening the drinking-and-driving enforcement at and near the border. This program consists of a series of discrete operations in which the California Highway Patrol (CHP) and the local San Diego Police Department (SDPD) conduct special patrols and sobriety checkpoints near the San Ysidro border crossing. During these operations, the foot patrols monitoring the pedestrian crossing area were increased. Early in the evening, the California law, which bars youths under aged 18 from entering Mexico unless accompanied by an adult, was rigorously enforced by the police checking IDs. OSC operations were conducted about every 60 Author: Lange ICADTS#(100) Page 1

3 days with especially strong efforts on holidays or at other times such as spring break when large numbers of late-night crossers were expected. As indicated below, each operation was supported by one or more media events designed to call attention to the enforcement effort. Border Survey Simultaneous with the county s funding of IHA s organizational activities, Pacific Institute applied for and received a grant to initiate a breath-test survey at the San Diego/Tijuana border crossing from 12 AM to 4 AM on Wednesday, Friday, and Saturday evenings of one week each month. A random sample of 100 of the several thousand individuals emerging from the customs inspection point each evening were asked to participate in the survey. The 5-minute interview collected information on age, gender, ethnicity, work status, home zip code, purpose of visit to Mexico, drinking quantity/frequency during the last month, number of drinks while in Tijuana, and driving plans for return trip home. The interview was followed by a breath test. Of those pedestrians approached, 84% agreed to participate in the survey. A hot deck imputation procedure was used to estimate nonparticipant missing data. A full description of the survey and analysis procedures is provided in Lange, Lauer, and Voas (1999). The Immigration and Naturalization Service (INS) makes use of turnstile counters to provide hourly totals of pedestrians entering the United States each day of the week. Their records from January 1, 1996, were available to the investigators, which provided 14 months of pedestrian data before the OSC began and 29 months after the OSC began. The random sampling procedure used in selecting interview participants permitted the weighting of each observation to project the results to the total INS hourly counts once the survey was underway (June 1997). Data/Media Advocacy Program From the beginning, data from the survey became an important source of information for organizing and managing the program. The data were used to help organize the OSC program, plan countermeasure activities, support program operations, and evaluate operational effectiveness: 1. Support for program organization: The earliest data demonstrated that the number of youths involved in cross-border binge drinking was much larger than generally recognized. This caught the attention of U.S. Department of Justice and local officials who convened a meeting of local law enforcement officials resulting in the establishment of the OSC program. The survey data were used by participating agencies to apply for federal, state, and local funding for overtime hours for police officers to carry out special border enforcement activities. Finally, survey data on the participants home zip codes were used to recruit police department participation in the OSC operations. Police departments from jurisdictions within San Diego and Orange Counties, which included the home locations of a substantial number of the border crossers, were approached to participate in the OSC program. 2. Support for operational planning: The survey data were also used to plan enforcement operations for the nighttime hours when most at-risk pedestrians would be heading home from the border. Such information included the home locations to which they would be traveling and the hour-by-hour number of drivers likely to be over the legal limit. 3. Support for enforcement operations: Once the OSC operations began, the IHA consortium initiated a special media advocacy effort to stimulate news coverage for each enforcement operation. Data from the survey provided news items around which a press conference or news event could be built to support the police activities. The information used at each operation varied to keep the information fresh and news worthy. On one occasion, the media advocacy program might focus on the number of underage youths crossing into Mexico and their BAC levels. On another, the focus might be on females crossing the border. Other data provided from these operations included college students, high school students, members of the military, and so on. In each case, information on the numbers crossing by hour of night and their BAC levels were provided for use in media activities. Author: Lange ICADTS#(100) Page 2

4 The availability of these data allowed the IHA to attract news organizations to press conferences or news events at the border. These events highlighted the upcoming enforcement operation and featured a spokesman from the police department. A key feature of these news events was attendance of spokespersons representing key constituencies parents, youth, city officials, the public in addition to the uniformed officer. This helped ensure that the public s impression would be that of strong community support for the police activity. Thus, the news events had two objectives: (1) to deter young high-risk drinkers from crossing the border to drink, and (2) to gain public support for the police departments to devote resources to deal with the cross-border binge drinking problem. 4. Support for measuring program progress: The border survey also provided a way to monitor the progress of the OSC program by providing trend data on the total number of youths returning late at night from Tijuana and their BACs. These data also allow an analysis of whether different subgroups college students, the military, high school students were being differentially affected by the program. Methods The program evaluation was designed to answer two research questions: (1) Did OSC reduce the total number of pedestrians returning late at night from Tijuana? (2) Did OSC reduce the number of returning pedestrians whose BACs put them at risk of arrest? The independent variable for this analysis was the number of radio, TV, and newspaper reports generated by the media advocacy effort. Because these news events were built around the enforcement operations, they were highly correlated with the concurrent police activities. The amount of media coverage was selected as the best quantification of the OSC effort because the size of the media advocacy effort and the response of the press were both related to the number of police used in the operation. Three dependent measures were used in the analysis. The first of these was the total number of pedestrians entering the United States from Tijuana on Fridays and Saturdays between 12 AM and 5 AM. The total number of pedestrians crossing into San Diego was available from the INS turnstile counts from January 1, 1996, to November 15, 1999, a total of 204 weekly data points (Friday and Saturday combined) covering 2,052,702 returnees. The other two dependent measures included the number of underage pedestrians who were potential zero tolerance violators because they were returning with BACs between.02 and.08, and the number of potential DUI violators returning with BACs of.08 or higher. These measures were based on 6,396 returnees tested on 28 weekends between June 1997 and November These test data were extrapolated to 48,773 returnees with BACs higher than.08 and 18,155 youths with BACs between.02 and 08. Figure 1. Cumulative media report measure used to represent OSC project Author: Lange ICADTS#(100) Page 3

5 Two analytical techniques were used to evaluate the impact of the OSC program. The INS counts of pedestrians entering the United States lent themselves to time series intervention analysis because a 14-month baseline period was available before project initiation. The project s effect was not represented by a single intervention point at its initiation in March 1997 but rather a cumulating function representing the media coverage across time from March 1997 to November The input function is shown in Figure 2. Prior analyses of the INS data had demonstrated that the number of pedestrians returning to San Diego is influenced by season (fewer in winter), by weather (fewer when it rains), and by Mexican elections when the bars close on Saturday nights. Variables representing each of these factors were entered into the analysis to account for their effects. Because some weekends within the series had no BACs sampled (resulting in missing values) and because the weekends sampled in each month were unequally spaced over time, ARIMA intervention models were not well suited for analysis of the BAC data. Instead, OLS linear regression was used. Figure 2 Weekly time series of pedestrians returning on Friday and Saturday nights from 12 AM to 4:59 PM The number of weekend pedestrian crossers were divided into three groups, based upon population projections from the BAC-tested samples: (1) adults >=.08, (2) youth >=.02, (3) all the rest. These three series, covering June 1997 through November 1999, were log transformed; then each was analyzed in an OLS regression in which the predictor variable was a linear time trend (values of 1-30, increasing by one each month) over the course of that 30-month period. Two monthly points were missing early in the series (July and September 1997) such that each of the three time series actually contained 28 data points. In addition to the monthly time trend variable, three weather variables (minimum and maximum temperature, and rainfall) were available as covariates, but none of these were significant and so were not included in the final models for each series. Although regressing a time trend variable is not necessarily the best way to assess/estimate a trend in a time series, the residuals were checked against the time trend to ensure that there were no sequential patterns to the errors (i.e., they were randomly distributed Author: Lange ICADTS#(100) Page 4

6 across time and not autocorrelated) and to verify that the data points near the beginning and end of the period did not exert undue influence over the regression fit. Results Figure 2 presents the 204-week time series of the number of pedestrians who entered the United States between 12 AM and 4:59 A.M. on Fridays and Saturdays combined. The vertical lines represent major enforcement/media advocacy operations. Table 1. Results of time series analysis pedestrians returning from Tijuana on Friday and Saturday nights Residuals DF Ad. Sum of Squares Residual B SEB T-Ratio Signif. AR <.001 AR <.001 SAR OSC RAIN <.001 VOTE <.001 CONSTANT <.001 Table 2. BACs of pedestrians returning from Tijuana between 12 AM and 4 AM on Friday and Saturday nights Unstandardized Coefficients BAC group B Std Error t Sig. Table 1 presents the results of the time series analysis. Two covariates had significant effects on the number of late night returnees: rain and vote (the Mexican election days). The OSC program was found to have an effect, significant beyond the.001 level, on the number of late-night crossers. The reduction produced by the OSC program was estimated to be 25.8%. Table 2 presents the results of the OLS analysis of the BACs of pedestrians crossing the border from 12 AM to 4 AM % Decrease BAC>= p= <21; BAC= p= All others p= from June 1997 to November During that period, the raw number pedestrians with BACs at.08 or above declined by an average of 11.6 per month or 37.3%. This decline was significant at the p=.01 level. However with only 28 data points, it was not significantly different from the 24% overall decline in the total number of crossers during that period. During the study period (June 1997 to November 1999), the number of underage drinking pedestrians declined on average by 7.7 per month or 51.2%. This reduction was significant at the p=.001 level. The reduction for this underage group was also significantly greater than the 24% overall reduction. The trend parameter for the group consisting of all other pedestrians not included in the first two groups had a nonsignificant reduction estimated at 16.2%. Discussion The results of this analysis present a strong indication that the OSC program has reduced by as much as 26% the number of pedestrians crossing into Tijuana on weekend evenings. An important question is whether those who have been deterred by the campaign are individuals who drink sufficiently to be at risk on the highway or whether the impact of the campaign has principally been to discourage crossing by light or nondrinkers. The analysis of the breath-test data from those crossers who participated in the border survey suggests that the program had a greater impact on the heavier drinkers who were more likely to be at risk for a DUI arrest or an alcohol related crash. In any case, it is clear that there is no evidence that the reduction in Author: Lange ICADTS#(100) Page 5

7 crossers attributed to the program occurred principally among those who were less likely to be at risk on the highway. This study has a number of strengths. Many cases were available for analysis. The analysis used significant controls for potentially confounding factors. At the same time, it must be recognized that there are several uncontrolled factors, which could not be accommodated in the analysis. The analysis presented could not test whether the observed linear down trend in high BAC crossers was a long term function that was present before the BAC survey began and therefore not a result of the OSC program. Further, OSC program was not the only activity related to the border drinking. The local government in Tijuana took action to reduce alcohol signage outside of the bars and the bar owners agreed to participate in a server training program. It also should be noted that analysis of the INS counts and breath-test data collected on motorists crossing the border into San Diego at the same hours as the pedestrians did not demonstrate a similar reduction in total numbers of crossers or in BAC levels. However, drivers entering the United States from Mexico are significantly different than pedestrians. The majority of the former are Hispanic Americans, many on their way back from visiting their families in Tijuana. Few are returning from visiting the bar scene in Tijuana. Acknowledgments This research was funded by the National Institute on Alcohol Abuse and Alcoholism under RO1-AA11913 and RO1 AA References Baker, J (1997) Drinking in Tijuana, Prevention File, Summer, 1997, p.2-6 Holder HD, Saltz RF, Grube JW, Voas RB, Gruenewald PJ, Treno AJ. A community prevention trial to reduce alcohol-involved accidental injury and death: Overview. Addiction. 1997;92:S155 S171. Lange JE, Voas RB. Youth escaping limits on drinking: Binging in Mexico. Addiction Lange JE, Lauer E, Voas RB. A survey of the San Diego Tijuana cross-border binging: Methods and analysis. Evaluation Review. 1999;23: McCarthy JD, Harvey DS. Independent citizen advocacy: The past and the prospects. Surgeon General's workshop on drunk driving: Background papers. Washington, DC: U.S. Department of Health and Human Services, Public Health Service, Office of the Surgeon; 1988: National Highway Traffic Safety Administration. Digest of state alcohol-highway safety related legislation. Washington, DC: U.S. Department of Transportation; th Edition. Treno AJ, Holder HD. Community mobilization, organizing, and media advocacy: A discussion of methodological issues. Evaluation Review. 1997;21: Author: Lange ICADTS#(100) Page 6