Crash Outcome Data Evaluation System
New: New Publication, 2005 Data Available
Welcome to the home page for the Wisconsin CODES Data Linkage Project.
The Wisconsin CODES Project is located at the Center for Health Systems Research and Analysis at University of Wisconsin - Madison.
In Wisconsin, the CODES linkage project operates as a multi-agency collaboration. Data from the Wisconsin Department of Transportation and the Department of Health and Family Services are linked and studied by analysts at the Center for Health Systems Research and Analysis. Funding for the project is provided by the National Traffic Safety Administration (NHTSA) through the Bureau of Transportation Safety (BOTS) within the Wisconsin Department of Transportation (WisDOT).
This web page is designed to be used by persons involved in Transportation Safety Research, Injury Research, as well as persons interested in some of the possible uses of probabilistic linkage.
We have tried to provide an overview of some of the research we have been involved in, as well as some information which we feel could be useful to the community.
For more information about the Wisconsin CODES Project contact Wayne Bigelow.
What is CODES? [see Presentation]
CODES (Crash Outcome Data Evaluation System) is a collaborative approach to obtain medical and financial outcome information related to motor vehicle crashes for highway safety and injury control decision making. It evolved as the result of the Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991 which provided funds to the National Highway Traffic Safety Administration (NHTSA) to report to Congress about the benefits of safety belts and motorcycle helmets for persons involved in motor vehicle crashes. To measure benefits in terms of reducing death, disability, and medical costs, NHTSA determined that statewide data were needed that included all persons involved in police-reported crashes -- those who were injured or who died as well as those who were not injured.
Wisconsin was one of seven states to receive a grant in 1992 from the U.S Department of Transportation (DOT), National Highway Traffic Safety Administration (NHTSA) to participate in the development of a Crash Outcome Data Evaluation System. The number of states involved in the national CODES project has increased to 20 States including:
Alaska Connecticut Hawaii Iowa Kentucky Maine Maryland Minnesota Missouri Nebraska Nevada New Hampshire New Mexico North Dakota Oklahoma Pennsylvania South Carolina South Dakota Utah Wisconsin
As a result of this grant and additional funding provided by the Bureau of Transportation Safety within the Wisconsin Department of Transportation (WisDOT), Wisconsin has developed a computerized system for linking Wisconsin Hospital Discharge data with Wisconsin Crash data. Because personal identifiers are limited in the data, a probabilistic linking process was used to merge hospital discharge and crash data. The presentation on Probabilistic Linkage which was given at the Association for Health Services Research Conference in 1999 explains more on this topic. The data has been linked for the years 1991-1999 for Wisconsin.
What can Linked data tell us?
The information available from linked data provides important information on the personal injury characteristics incurred from crashes, as well as a the costs associated with crashes.
Linked data can identify the types and costs of injuries resulting from crashes.
Linked data can provide information on the injuries incurred in crashes by vehicle and crash characteristics. Percent of Crash Related Brain Injuries by Crash Configuration, Wisconsin 1997
Linked data can provide information on the number of hospitalizations and hospital charges by crash characteristics. Percent of Crashes, Hospitalizations, and Hospital Charges by Crash Configuration, Wisconsin 1997
Linked data can provide information on the effectiveness of safety equipment, including seatbelts and airbags. The types of injuries sustained or not sustained using the equipment.
Linked data can provide information on crash characteristics and on the types and cost of injuries, by community, county and road type. Percent of Crashes and Hospital Charges by Road Type, Wisconsin 1996
Data Limitations
Data linkage has proven to be an efficient, cost-effective way to create an injury surveillance system from existing data sources designed for other purposes. As with all data systems, a linked data file has limitations. Some arise from the linkage methodology, and others are inherent in the primary data sources.
Some crash-related hospitalizations are missing from the linked data set. In our experience, the linked data is missing about 20% of all crash related hospitalizations. These unlinked cases result in an underestimate of the total motor vehicle crash injury problem. However, there is no reason to expect that the cases not linking are different from cases which do link. Hospitalizations may be excluded from the data set for a variety of reasons, including:
- People who are in Wisconsin crashes but transported out of state for treatment are excluded.
- People in unreported crashes who have no records in the crash data, and therefore can't be linked are excluded.
- Similarly persons whose crash records contain insufficient identifying information (missing birth date or sex) can't be linked with the hospital data file.
Some crash types may be under represented in the DOT crash data. If a pedestrian or bicyclist is injured but the crash doesn't involve a motor vehicle the crash may not be reported to the DOT. Uninjured motorcyclists also may be underrepresented.
There may be biases in the reporting of some variables in the crash data. Eighty-five percent of crash occupants reportedly use seat belts, even though observational studies have determined the statewide rate of seatbelt use to be approximately 55% to 60%. 0ther information, such as alcohol use is likely to be selectively reported.
Despite limitations, a linked data base is an extremely useful tool for documenting the nature and magnitude of crash injuries and evaluating the effectiveness of specific countermeasures. Nonfatal motor vehicle crash injuries sometimes are very severe, and can result in lifelong disability. This makes them expensive to treat. In an era of spiraling health care costs, public health professionals should explore all possible means for preventing these injuries. A linked data system contains information on occupant, vehicle and environmental factors. which can be used for problem identification at the national, state, regional and local levels.