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Show mentioned above. Thus, probabilistic linkage allows CODES researchers to access information from a variety of sources to obtain a more complete and accurate assessment of the crash event. Figure 1 shows how probabilistic linkage can aid in completing the picture of motor vehicle morbidity, and that fatalities are the tip of the iceberg when it comes to studying motor vehicle crashes. Since these databases were collected independently from different sources, there are no database keys that identify person X in the crash file as person Y in the hospital file. For this reason, techniques such as probabilistic record linkage are needed to combine these databases. Record linkage is accomplished by comparing common data fields in two different files, such as the date of birth or the gender of a patient. The comparisons of numerous data fields lead to a judgment that two records refer to the same patient event (and should be linked) or that the records do not refer to the same patient event (and should not be linked). This judgment is based on the cumulative agreement and disagreement of field values. Probabilistic linkage software accomplishes this task mathematically, rather than relying on the subjective impression of a human clerical reviewer. More thorough treatments of the subject have been previously published (Cook, Olson and Dean, 2001; Jaro, 1995; Newcombe, 1988). Combining results from the Utah CODES linkage with data from the other six states, researchers from NHTSA delivered a report to congress in February 1996 on nearly 900,000 drivers and passengers of vehicles that were involved in a motor vehicle crash during 1991. The report shows that seatbelts are very effective at reducing injury following a motor vehicle crash and effectiveness increases with the severity of injury studied. For instance, while seatbelts were 20% effective at preventing injuries as a result of a motor vehicle crash, they were 60% effective at preventing death following a motor vehicle crash. For crash victims that are admitted to the hospital, the use of a seatbelt lowers the average hospital charge by 55% (Johnson and Walker, 1996). Current Activities Since the report to Congress, the staff at Utah's CODES project has continued to gather, probabilistically link and conduct research on statewide databases. These databases include vital statistics databases (death certificates, birth certificates, and fetal death certificates) and driver license databases (moving citations and driver medical conditions) in addition to the original motor vehicle crash, emergency medical services, emergency department, and hospital discharge databases. Currently the Utah CODES project has linked the motor vehicle crash records to hospital discharge records for years 1992 - 1998, to emergency department and emergency medical services records for years 1996 - 1998, to vital statistics data for 1992 to 1999, and to driver license databases for years 1992 - 1996. Presentations of this research have been given at a wide variety of national and international meetings including: American Public Health Association, Association for the Advancement of Automotive Medicine, International Forum for Traffic Records and Highway Information Systems, and the National Congress on Childhood Emergencies. Research on Utah CODES linked databases has also resulted in several peer-reviewed publications. These studies have focused on subpopu-lations of drivers at risk for a motor vehicle crash such as teenagers (Cvijanovich et al., 2001b), older drivers (Cook et al., 2000), and drivers with specific medical conditions (Diller et al., 1999; Vernon et al., 2001; Vernon et al., 2002); special types of vehicles including all terrain vehicles (ATV) (Cvijanovich et al., 2001a; Cvijanovich et al., 2000) and snowmobiles (Skokan et al., 2001); the consequences of not properly wearing a seatbelt (Knight et al., 2001); the effectiveness of safety restraints for children (Berg et al., 2000; Corneli, Cook and Dean, 2000); the effect of known over reporting of seatbelt use in police crash records (Dean, Reading and Nechodom, 1995); and general probabilistic linkage methodology (Cook, Olson and Dean, 2000; Cook, Olson and Dean, 2001; Dean et al., 2001). The Utah CODES project personnel have been active advocates for traffic safety in the state. Data linked and analyzed by Utah's CODES project has been presented at the Utah legislature in support of traffic-related bills. Linked data were integral in educating Utah policy makers on the importance of passing a primary seatbelt law, which requires all drivers and passengers under the age of 19 years to wear a seatbelt and all children four years of age or younger to be restrained in a child safety seat. Linked data were also used in the campaign to promote graduated driver licensing laws in our state. This program removes driving restrictions in stages as novice, teenage drivers gain maturity and experience, until full licensure is granted. In cooperation with the Utah Department of Public Safety, Highway Safety Office, Utah CODES has compiled the Utah Crash Summary since 1994. This document contains detailed tables and graphs of all Utah public-roadway reported motor vehicle crashes and their participants plus sections on certain subpopula-tions such as pedestrians, bicyclists, alcohol and drug related crashes, and teenage drivers. As a companion to the crash summary, several fact sheets are produced for each section. Both the crash summary and fact sheets are available at the Utah CODES website, http:// www.utcodes.org. In addition to providing data for traffic safety advocates, Utah CODES personnel have served as members Utah's Health: An Annual Review Volume VIII 21 |