2003 National Asthma Survey (NAS) Four-State Sample

Data from the 2003 National Asthma Survey (NAS) four-state sample were released by the Centers for Disease Control and Prevention (CDC) National Center for Health Statistics (NCHS). This survey, a module of the State and Local Area Integrated Telephone Survey (SLAITS), was sponsored by CDC’s National Center for Environmental Health (NCEH). Two random-digit-dial (RDD) studies were fielded for the NAS: a national study and a four-state study (Alabama, California, Illinois, and Texas). This data release only concerns the four-state sample. At this time, we anticipate that the national sample data will be publicly available by the end of September 2005.

The SLAITS NAS was designed to describe the health, socioeconomic, behavioral, and environmental predictors that relate to better control of asthma, and to characterize the content of care and limitations of persons with asthma. The NAS data may assist in identifying national and state-level program needs for adults and children, and to examine trends in asthma prevalence, severity, and management. The NAS included an extensive battery of questions about the history of asthma (symptoms and episodes); health care utilization; knowledge of asthma/management plan; modifications to the environment; medications; family history of asthma; and demographic information.

The design of the four-state study does NOT permit the calculation of prevalence rates, but instead provides analytic data for asthma-positive persons. The national sample data can be used to calculate prevalence rates. The four-state study immediately screened households for the presence of someone with asthma. If no one was reported to have asthma, the interview terminated. In household where asthma was reported, up to one asthma-positive adult and one asthma-positive child were randomly selected for a detailed interview regarding asthma management and treatment.

The four-state sample was fielded from March 1, 2003 to March 10, 2004. In the four-state study, 48,185 households were screened for the presence of someone with asthma. An average of 1,435 interviews were completed in each state, for a total of 5,741 completed interviews with persons with asthma. The number of completed interviews varied by state, ranging from 1,313 to 1,507. If the sampled person was an adult, the respondent was that person. If the sampled person was a child, the respondent was the parent or guardian who knew the most about the child’s health and health care. The weighted detailed asthma interview CASRO response rate for the four-state study was 48.5%.

A list of variables on the data set, as well as sample SAS programs for reading and formatting the data, are available on the web site for the National Asthma Survey at: http://www.cdc.gov/nchs/about/major/slaits/nas.htm

A methodology report titled “Design and Operation of the National Asthma Survey, 2003” is forthcoming. It will be available at the NAS web site when it is approved for release. This detailed report will contain information on the sample design, proxy interviews in the national study, questionnaire design, interviewer training, data collection, quality control, weighting and estimation procedures, and data files.

The CDC encourages you to make use of these data, and to keep them informed of any publications or presentations based on these data. Any questions or comments about these data can be sent to Kathleen S. O’Connor at This e-mail address is being protected from spam bots, you need JavaScript enabled to view it (301-458-4181).