Center for Health Systems Research and Analysis
College of Engineering
University of Wisconsin-Madison
The Wisconsin Crash Outcome Data Evaluation System (CODES) project is a collaboration between the Wisconsin Department of Transportation, the Department of Health Services and the University of Wisconsin to link medical and financial outcome information with motor vehicle crash information for highway safety and injury control decision-making.
The Department of Health Services uses national standardized probabilistic record linkage software and processes to link Wisconsin Hospital Discharge data and Emergency Department Visit data with Wisconsin Motor Vehicle Crash data. Linkage between Wisconsin crash and hospital discharge records began in 1992. In 2002 linkage between crash and emergency department records began. VIN data have been added to the linked files since 1994. The Wisconsin and Minnesota CODES projects collaborate in linking Wisconsin crashes to Minnesota hospital records for the Wisconsin's westernmost counties. An agreement with the Iowa CODES project to perform similar cross-border linkages is in process.
This provides Wisconsin with a cost-effective way to create a motor vehicle crash injury surveillance system from existing data sources currently being used for other purposes. The CODES linked database is an extremely useful tool for documenting the nature and magnitude of crash injuries and evaluating the effectiveness of specific countermeasures.
The CODES linked file is used by the State Highway Safety Office for program development, researchers at UW Center for Health Systems Research and Analysis, and the Medical College of Wisconsin to study injury related events, outcomes, and costs experienced in crashes. Cost data are used by communities to justify traffic safety expenditures, and by the Legislature in public policy making.
State level summary reports for motor vehicle crashes involving passenger vehicles (1996-2005), motorcycles (1999-2005), bicycles (1999-2005) and pedestrians (1999-2005).
Community Crash Reports for all Wisconsin Counties and for 70 cities/urban areas are available for the period of 2001-2005.
General Hospital/Emergency Department Injury Reports are also available for cities, counties and the state as a whole for 2002-2005.
These linked data provide information to the UW Center for Health Systems Research and Analysis about what kind of personal and aggregate injury events and outcomes crash victims experience, as well as the types and costs of injuries that occurred. These linked data provide Wisconsin with a cost effective way to create a motor vehicle crash injury surveillance system from existing data sources currently being used for other purposes. The CODES linked database is an extremely useful tool for documenting the nature and magnitude of crash injuries and evaluating the effectiveness of specific countermeasures.
A variety of state and local reports are available on the Wisconsin CODES website: www.chsra.wisc.edu/codes
Some crash-related hospitalizations are missing from the linked data set. In our experience, the linked data are missing about 20% of all reported crash related hospitalizations. These unlinked cases may 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 and ED visits 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 may be excluded, although Wisconsin/Minnesota data linkages have largely resolved this issue for 2001-2005.
- People in unreported crashes who have no records in the crash data, and therefore can't be linked are excluded. Currently, Wisconsin doesn't require crash reports to be filed if the expected damage involved is less than $1000 and there are no obvious injuries.
- Persons whose crash records contain insufficient identifying information (missing birth date for example) may not be able to be linked with the hospital and ED data files.
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 incident will 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 70% to 75%. Other information, such as alcohol use, may also be selectively reported.