DefinitionThe [http://www.cdc.gov/brfss/index.html Behavioral Risk Factor Surveillance System (BRFSS)] is an ongoing telephone survey conducted by states with guidance from the Centers for Disease Control and Prevention (CDC). The survey collects health and behavior-related information from a random sample of adults aged 18 years and older for all 50 states, District of Columbia, and three territories. It is the longest continuously running phone survey in the world, and it is completely anonymous. Alaska has maintained a [http://dhss.alaska.gov/dph/Chronic/Pages/brfss/default.aspx BRFSS] program since 1991.
NumeratorEach year, the BRFSS survey asks questions on a wide range of demographic variables and health topics such as quality of life, chronic diseases, risk factors, protective factors, and treatment. Data from these questions are used to create a large number of health indicators. For these indicators, numerators typically consist of the weighted number of adults meeting conditions of the question who responded positively (or negatively, in some cases) to the BRFSS survey question of interest.
DenominatorDenominators for the health indicators typically consist of the weighted number of adults meeting conditions of the question who provided valid responses to the BRFSS survey question of interest.
Data Interpretation IssuesData from the AK BRFSS should be considered representative of all adults (18+) within Alaska. Between 1991 and 2010, data were collected using a random sample of all possible landline telephone numbers. Since 2011, the telephone survey has incorporated both landline and cellular telephones with sampling proportional to the distribution of cellular telephones. Prior to analysis, data are weighted to represent the population distribution of adults by sex, age group, and area of residence. The introduction of a new weighting methodology--[https://www.cdc.gov/mmwr/preview/mmwrhtml/mm6122a3.htm iterative proportional fitting or "raking"]--has allowed more population and socioeconomic variables to be considered than was possible using the previous post-stratification method. Post-stratification weights (i.e., number of surveys divided into population estimates of age within sex within region) were used for Alaska data from 1991 through 2006; raking weights have been applied to data from 2007 onward. For more on this methodological change see: [http://dhss.alaska.gov/dph/Chronic/Pages/brfss/method.aspx].
With all surveys, some error results from nonresponse (e.g., lack of a landline or cellular telephone in the household, refusal to participate in the survey or to answer specific questions) and measurement (e.g., social desirability or recall bias). Error is minimized by use of strict calling protocols, good questionnaire design, standardization of interviewer behavior, interviewer training, and frequent, on-site interviewer monitoring and supervision.
A second BRFSS-like survey, the Supplemental BRFSS, has been conducted in Alaska since 2004. The Supplemental BRFSS survey is conducted using identical methodology as the Standard BRFSS and allows a doubling of the BRFSS sample size for those measures included in both surveys.
Why Is This Important?This surveillance system is an important source of health-related data used to guide public health programs and policies at the state and local level. The BRFSS is the only source for representative statewide data for many chronic health conditions, risk factors, and injuries.
The content of the national BRFSS questionnaires can be found at [http://www.cdc.gov/brfss/questionnaires/index.htm]. Alaska questionnaires are available at: [http://dhss.alaska.gov/dph/Chronic/Pages/brfss/default.aspx] for the standard survey and at: [http://dhss.alaska.gov/dph/Chronic/Pages/brfss/supplemental.aspx] for the supplemental version.
Other ObjectivesAlaska Native people in analyses of the BRFSS refers to any mention of American Indian or Alaska Native heritage when enumerating racial and ethnic background. Individuals who indicate multiple races including American Indian/Alaska Native are considered Alaska Native in the data. When race and ethnicity are consider concurrently, Hispanic individuals with American Indian/Alaska Native heritage are combined into the Alaska Native (any mention) group and removed from the Hispanic class.
This definition of the Alaska Native group is intended to conform to the eligibility requirements for access to Alaska Native Tribal Health Consortium health care services.
How Are We Doing?The BRFSS maintains data suppression and data quality rules. The minimum sample size needed to ensure a representative sample of Alaska adults is 2,500 completed surveys per year. Data in static prevalence tables are not reported if the unweighted sample size for the denominator is less than 50. Relative standard errors (RSE) larger than 30% are considered unreliable and noted as such. Overall response rates have remained consistently above 60%, though rates have declined over time following a national trend.
How Do We Compare With the U.S.?States have the option to ask optional modules and state-added questions that are not asked uniformly across states. Optional modules are questions on specific topics that states elect to use on their questionnaires. Although the modules are optional, CDC standards require that if they are used, they must be used without modification. These modules have been cognitively tested. State-added questions are questions added to the survey that have not been designed or field-tested by the CDC. This includes Optional Modules where wording has been changed, or questions have been added or eliminated from the complete module.
The BRFSS is intended to provide the prevalence of health indicators for states, DC, and territories. It is not intended to be the national surveillance system, which is limited to the NHANES and NHIS surveys.
What Is Being Done?Data from the BRFSS are critical for planning throughout and beyond the [http://dhss.alaska.gov/dph/Chronic/Pages/default.aspx Section of Chronic Disease Prevention and Health Promotion (CDPHP)] to ensure health indicators important to Alaskans are being measured. Furthermore, BRFSS data are used to measure progress towards 7 [http://hss.state.ak.us/ha2020/ Healthy Alaskans 2020 (HA2020)] goals.