OBJECTIVES AND DESIGN OF THE BEHAVIORAL RISK FACTOR SURVEILLANCE SYSTEM

L INTRODUCTION By the early 1980s, it was evident from scientific research that personal health behaviors played a major role in premature morbidity and mortality, but no data were available on a state-specific basis. This was viewed as a critical deficiency, since state health agencies have the primary role of targeting resources to reduce behavioral risks and their consequent illnesses, and national data may not be appropriate for any given state. At about the same time, telephone surveys emerged as an acceptable method for determining the prevalence of many health risk behaviors. Telephone stu-veys were especially desirable at the state and local level, where the necessary expertise and resources for conducting area probability sampling for in-person household interviews were not likely to be available. As a result, surveys were developed to monitor state-level prevalence of the behavioral risks associated with premature morbidity and mortality among adults. Behavioral .data were thought to be especially useful for planning, initiating, supporting, and evaluating health promotion and disease prevention programs. Initial point-in-time state surveys were conducted in 29 states from 1981-1983. In 1984, the Behavioral Risk Factor Surveillance System (BRFSS) was established by CDC, with 15 states participating in monthly data collection. Although designed to collect state-level data, a number of states from the outset stratified their samples to allow them to estimate prevalence for regions within their respective states. By 1994, all 50 states and the District of Columbia were participating; as of 1998, Puerto Rico also was collecting monthly data and the Virgin Islands and Guam were conducting point-in-time surveys. A standard questionnaire was developed at CDC for states to use to provide data that could be compared across states. The initial survey primarily included existing questions from national surveys such as the National Health Interview Survey. The basic questionnaire was designed to last no more than ten minutes so that states could add their own questions. In general, the BRFSS gathers information on health behaviors related to the leading preventable causes of death, including physical inactivity, injury, weight control, alcohol consumption, tobacco use, and HIV-AIDS. It also collects data on preventive health practices such as mammography use. For data collection, states were historically encouraged by CDC to use cluster designs based on the Waksberg method; however, even for the initial 29 pointin-time surveys, there was state variability; nine of these states used simple random samples. Currently, the vast majority of states use disproportionate stratified sampling (DSS). One important characteristic of the BRFSS is its flexibility. It permits states to add questions of their own design, but is uniform enough to allow state-to-state comparisons for certain questions. Participating states use these data for many purposes. Among these are to identify demographic variations in health-related behaviors, target services, address emergent and critical health issues, propose legislation for health initiatives, and to measure progress towards state and national health objectives. The system's broad network for information gathering also enables states to evaluate their disease prevention and health promotion efforts.