The Behavioral Risk Factor Surveillance System
The Behavioral Risk Factor Surveillance System (BRFSS) is an annual statewide telephone surveillance system designed by the Centers for Disease Control and Prevention (CDC). Surveillance is conducted on a monthly basis to collect data on modifiable risk behaviors, preventative health practices and health-related conditions contributing to the leading causes of morbidity and mortality in the population. North Dakota’s sample represents randomly selected residents of the non-institutionalized adult household population, ages 18 years and older. Information provided by BRFSS is not available from other sources.
As the only source for comprehensive state-specific population-based estimates of prevalence on preventative health practices and risk behaviors, BRFSS is an important tool for decision-making throughout the public health community. Public and private health authorities at the federal, state and local levels rely on BRFSS to identify public health problems, design policies and interventions, set goals, and measure progress toward those goals. On occasion, the North Dakota BRFSS works with the local public health community to oversample or administer point-in-time health surveys at the county level. The primary focus of this effort has been to acquire data for evaluation and decision-making at the local level.
BRFSS is used nationwide under the direction of CDC so that, while conducted independently, survey methods are standardized across all 50 states, three territories and the District of Columbia. As a result, comparisons can be made to other states and the national average. CDC provides a core questionnaire that the states may choose to supplement with optional modules and state-added questions. Statewide monthly samples are edited and aggregated into yearly datasets. BRFSS activities are supported with financial and technical assistance from CDC. The North Dakota BRFSS was initiated in 1984.
Scientific research clearly shows personal health behaviors play a major role in premature morbidity and mortality. Smoking, physical inactivity, poor eating habits, obesity, alcohol abuse and other risk factors can lead to a variety of chronic health problems and increase the risk of communicable diseases such as AIDS, sexually transmitted diseases and vaccine-preventable diseases. Injuries from violence and accidents also may be caused by behavioral risks. Consequently, making substantial improvements in health outcomes (illness, death, injury and disability) requires improving health behaviors. As a result of this evidence, public health professionals are focusing on ways to help people change their behaviors to reduce risks and prevent illness or premature death. Community efforts to improve health depend on measurement of both health outcomes and health behaviors to design and measure the impact of local health intervention efforts.
Health outcomes can be measured in medical records and vital records, such as birth certificates and death certificates, but measuring the behaviors that have such a profound impact on health requires either observing what people do or asking them what they do. Structured interviewing (i.e., surveying) of large numbers of individuals randomly selected from the population (sampling) has been the most commonly employed and most economical method for measuring behavior.
This information is gathered through the Behavioral Risk Factor Surveillance System (BRFSS). In the early 1980s, the Centers for Disease Control and Prevention (CDC) worked with several states, including North Dakota (N.D.), to create the BRFSS and address these behavioral health risks. This unique, state-based surveillance system is the largest continuously conducted telephone health survey in the world.
In the early 1980s, national estimates of health risk behaviors among U.S. adult populations had been periodically obtained through surveys conducted by the National Center for Health Statistics (NCHS); however, these data were not available on a state-specific basis nor were the data gathered in a systematic manner. State health agencies with the primary responsibility to reduce behavioral risks and their consequent illnesses viewed this lack of state-specific data as critical. The CDC concurred and recognized that state and local agency participation was necessary to achieve national health goals.
Thus, the BRFSS surveys were developed and conducted to monitor state-level prevalence of the major behavioral risks associated with premature morbidity and mortality. The CDC collaborated with individual states to develop the BRFSS survey questions, which were designed to gather data from adults about their self-reported health and health-risk behaviors.
To determine feasibility of behavioral surveillance, initial point-in-time state surveys were conducted in 29 states from 1981 to 1983. In 1984, the CDC established the Behavioral Risk Factor Surveillance System (BRFSS), and 15 states, including North Dakota, participated in monthly data collection. Although the BRFSS was designed to collect state-level data, from the outset a number of states stratified their samples to allow them to estimate prevalence for regions within their respective states.
CDC developed a standard core questionnaire for states to use to provide data that could be compared across states. By 1994, all states, the District of Columbia, and three territories were participating in the BRFSS.
The ND BRFSS is a random-sample telephone interview survey of North Dakota’s adult population. The BRFSS is the primary source of information on health risk behaviors related to chronic disease and injury among adult populations in our state. North Dakota has been collecting behavioral risk factor data continuously since 1984. Interviewing is conducted every month of every year, and data are analyzed on a calendar-year basis. The annual sample in N.D. is about 5,000 non-institutionalized adults ages 18 and older.
The BRFSS attempts interviews with adult North Dakota residents (18 years of age or older) whose household telephone number is included in the sampling frame.
First, interviewers must identify if the number they have dialed is a household. A household is eligible if it is a housing unit with a separate entrance where occupants eat separately from other persons on the property and is occupied by its members as their principal or secondary place of residence. Non-eligible households include the following: 1) Vacation homes not occupied by household members for more than 30 days per year; 2) Group homes (e.g. sororities and fraternities, halfway houses, shelters); and 3) Institutions (e.g. nursing homes, college dormitories).
Once a telephone number is determined to be a household, a random selection procedure is used to select the appropriate household member to interview. Household members include all related adults ages 18 years or older, unrelated adults, roomers and domestic workers who consider the household their home even though they may not be home at the time of the call. A household does not include adult family members who are currently living elsewhere, such as at college, a military base, a nursing home or a correctional facility.
A BRFSS respondent is 18 years of age and older. The first question on the BRFSS questionnaire regarding household selection asks how many members in the household are 18 years of age or older. If the answer is one and the person answering the telephone is that adult, the interviewer proceeds to the first question on the questionnaire. If the response indicates that there are five or more adults, the interviewer probes the respondent to ensure that they all are 18 years of age or older, that all currently are living in the household and that the household is not a group home or institution.
The next question asks how many of the adults are men and how many are women. The interviewer enters the respondent's answers into a computer and the computer randomly selects one adult to complete the BRFSS. The interviewer asks to speak to the selected adult.
The BRFSS is used by all states, the District of Columbia and three territories through funds disbursed by CDC and supplemented by state program funds. The BRFSS collects information from adults on health behaviors and preventive practices related to several leading causes of death and provides data for many purposes, including:
- Assessing risk for chronic diseases.
- Identifying demographic differences and trends in health-related behaviors.
- Designing and monitoring health interventions and services.
- Addressing emergent and critical health issues.
- Formulating policy and proposing legislation for health initiatives.
- Measuring progress toward achieving state and national health objectives.
The BRFSS can be adapted to meet state-specific needs, while still allowing for state-to-state and regional comparisons. It also can be used to assess special populations, such as military personnel and members of health maintenance organizations.
Technological and cultural changes are posing challenges to survey research. One of the most significant challenges has been the rapid increase in "cell phone only" households, especially among young adults and certain minority populations.
Because cell phones have so quickly replaced landline phones among certain populations, especially young adults, it has been difficult to obtain a true representative sample of those populations during the mid- to late- 2000s. The response-rate problems likely resulted in less accurate prevalence estimates for some behaviors or conditions more prevalent in those populations. For example, prevalence of cigarette smoking, which is known to be more prevalent among young adults, may have been underestimated for several years. Explanation of the changes and their impacts will accompany future data reports.
Starting with reporting of our 2011 data, the North Dakota BRFSS will be using a new method for weighting data that more accurately reflects the actual population of each state. In addition, the BRFSS has become a "multi-mode survey," using several modes of data collection — including landline telephone interviews, cell phone interviews, and in some states, mail follow-up surveys for some respondents who don't want to respond by phone. Alternate methods of sample selection are being researched.
Consequently due to the new weighting methodology, the 2011 data will break trend lines and become a new baseline for future analyses. The end result will be improved scientific validity of BRFSS data. These improvements will ensure that the BRFSS continues to be the leading source of essential behavioral data for public health planning, program development, education and evaluation.