Table of Contents

Introduction

Background

Indiana has the distinction of being a pioneer among the states participating in the Behavioral Risk Factor Surveillance System (BRFSS). Over the past few decades, many of the public health promotion initiatives of the Indiana State Department of Health (ISDH) have focused not only on infectious diseases and their prevention, but also on chronic disease prevention and how certain behavioral risks are associated with these diseases.

Since 1984, the ISDH has entered into a yearly cooperative agreement with the Centers for Disease Control and Prevention (CDC) to develop and implement the BRFSS survey in Indiana. This national survey monitors modifiable risk factors associated with chronic and communicable diseases by collecting information from adults on their health behaviors and preventive practices. Since the early years, continuous improvement in the collection process and analysis of the data has provided public health professionals with a wealth of information that has aided in promoting healthy lifestyles.

Health risk factors of adults, many of which are behavioral in nature, are examined in the BRFSS. The surveys are conducted on a continuous basis throughout the year to determine the proportion of Indiana residents who engage in health behaviors that increase the probability of both positive and negative health outcomes. These behavioral risk factor prevalence data play a vital role in developing public policy and monitoring achievement of public health goals.

The BRFSS is the largest continuously conducted health survey in the world. It was developed by the CDC to collect data on major behavioral risk factors that contribute to premature death and disability. Emerging health concerns and other critical health issues are also included in the survey.  With this elaborate surveillance system, the BRFSS monitors health behaviors in all states, the District of Columbia, and three U.S. territories, which permits state and regional comparisons, as well as trend analyses.

Core questions, which are used by all participating states each year, are developed jointly by the CDC and the participating states. Standard modules on specific topics may be added to accommodate a state's individual surveillance needs. States may also add questions designed to gather data on local or regional needs.

Over the years, Indiana's BRFSS program has increased surveillance coverage in the following areas: assessment of general health status, use of health care resources, the prevalence of selected chronic conditions, knowledge and awareness of AIDS and HIV, awareness and prevalence of clinical screening procedures, and injury issues.

Additional surveillance efforts of the BRFSS program in Indiana have doubled the statewide sample size since the first survey was done, expanded the use of rotating modules specific to program areas within the ISDH, increased the number of state-added questions, and aided several counties with the development of their own surveys to monitor health risk factors in specific geographic areas.

Goals and Objectives of the BRFSS

The ISDH, in partnership with a variety of public and private programs, is responsible for planning, implementing, evaluating, and tracking disease and injury prevention programs in Indiana. The ultimate goal of the national BRFSS survey is to provide valid data to assist in these tasks. To help states achieve these goals, the CDC has established the following objectives for all BRFSS programs:

· Determine prevalence of personal health behaviors associated with the leading causes of premature death.

· Increase public awareness of lifestyles that can significantly influence health and well-being.

· Monitor behavioral risk factors over time and focus on factors that are not improving.

· Assess progress in meeting the national health objectives for health promotion and disease prevention.

· Assess the impact of state legislation on behavioral risks.

· Share BRFSS data with state and local agencies involved with health-related issues.

The Questionnaire Design

The BRFSS questionnaire has three basic parts: 1) a set of core questions used by all participating states and U.S. territories, 2) standard modules on selected topics that may rotate from year to year, and 3) state-added questions, which are developed by individual states and relate to state and local health issues. The core and standard modules are jointly developed by the states and the CDC. Because all participants use the same core questions, data can be used for comparative purposes and trend analyses.

Core health-related topics include: health status, health care access, awareness of selected medical conditions (hypertension, diabetes, and high cholesterol), injury control, tobacco and alcohol use, women's health issues and the use of certain preventive health measures, awareness and attitudes concerning HIV/AIDS, and prevalence of testing for HIV infection.  In addition to questions concerning health-related behaviors, respondents are asked to provide demographic information such as age, sex, race, marital status, household income, employment status, and educational level.

Standard modules assess such risk factors as weight control, oral health, participation in leisure time and physical activities, consumption of fruits and vegetables, consumption of alcohol, and the use of smokeless tobacco.

Methodology

Indiana's sample size for 2004 was 6,490 randomly selected Indiana residents aged 18 years or older. A disproportionate stratified random sample design was used to generate the sample of telephone numbers. In this design, information obtained from previous surveys was used to classify 100-number blocks of telephone numbers into strata that were either likely or unlikely to yield residential numbers. Telephone numbers in the likely stratum were sampled at a higher rate than numbers in the unlikely stratum.

A sample was drawn independently by randomly sampling the telephone numbers within each stratum. Then, when an interviewer called a sampled household, one adult living in the household was randomly selected to be the respondent. The completed survey sample was designed to produce a representative sample of all adult Indiana residents.

The Interview Process and Quality Assurance Measures

In 2004, the ISDH contracted with Clearwater Research, Inc., for telephone interviewing and data preparation. A computer-assisted interviewing system (CASS-CATI) was used in the interview process. A CDC-developed protocol was followed to process the data. When monthly interviewing was completed, the data were summarized utilizing a computer program provided by CDC. The summary and the data were then submitted to CDC whose staff edited, corrected, compiled, and weighted the state data into an annual file that was provided to the ISDH BRFSS Program Coordinator.

Quality assurance of the survey data is mandated by CDC. The questionnaires were edited daily to assure proper completion. Callbacks were done randomly, on a spot-check basis, to confirm that interviews had been conducted as indicated.

Response Rates

The objective of the CDC data quality protocol is to provide the most accurate data possible. Because non-responses tend to bias the results of a survey, special attention was given to minimizing the non-response rate. The extent to which completed interviews were obtained from among all phone numbers selected is indicated by several different measures of response rate. A high response rate indicates a lower potential for bias in the data.

An estimate of response rate was calculated in order to measure the degree of bias in each state's data. The measure was developed by the Council of American Survey Research Organizations (CASRO). It is defined below.

CASRO -

This estimate reflects telephone sampling efficiency as well as the degree of cooperation among eligible respondents who were contacted. It includes the number of attempted interviews that were not completed for any reason. Cooperation elements include: completed interviews, refusals, early terminations, or the selected respondent was not available at a convenient time. Sampling efficiency elements include non-working numbers, rings but no answer, nonresidential numbers, busy signals, no eligible respondent at the number, language barriers, and other communication problems.

One of the CDC data quality objectives is to reach a CASRO response rate of 75 percent or higher. The median value for participating areas in 2004 was 52.7 percent.  Indiana's CASRO response rate in 2004 was 49.5 percent.

Survey Limitations

The BRFSS survey relies on self-reported data and has certain limitations. These limitations should be understood in the interpretation of the data. Many times, respondents have the tendency to underreport some behaviors that may be considered socially unacceptable, unhealthy, or even illegal such as high alcohol consumption, drinking and driving, or not using seat belts. Conversely, respondents may overreport behaviors that are considered desirable (the amount of exercise done, low body weight, or regular health screenings). Some information is also affected by the ability of the respondent to recall past behaviors and respond accordingly. The validity of survey results depends on the accuracy of the responses to the survey questions from recalled past behaviors.

The BRFSS survey excludes households without telephones, which may result in a biased survey population due to underrepresentation of certain segments of the population. Additionally, breaking down the data into smaller categories decreases the sample size of the original risk factor categories, thereby decreasing the ability to determine statistically significant differences.

Finally, it should be noted that weighting the data by age, race, and sex distribution was done in order to correct for over- or underrepresentation of all groups. Prevalences based on denominators of less than 50 respondents were considered statistically unreliable.

Weighting of Data

The data as collected from the respondents in the BRFSS survey are unweighted data. The number of different telephone numbers that reach each household, the number of adults in each household, and the number of completed interviews in each cluster are considered in the weighting process. After adjusting the raw data to these three factors, the data are adjusted further using the Indiana age-race-sex group distribution so that the weighted sample data produce demographic distributions that correspond closely to the state population.

The National BRFSS Prevalence Summary

The Behavioral Surveillance Branch of the CDC provides a BRFSS summary prevalence report on selected risk factors and preventive health measures from its survey for each participating state. This summary report consists of tables capturing data provided by each participating state indicating whether individual states are at, above, or below the national median prevalence value.

The summary also provides a tool to determine how states compare with each other and to the Healthy People 2010 objectives related to the risk factors that BRFSS measures.  Summary information includes the name of the participating state, the sample size, the prevalence of the risk behavior, and the confidence interval for the prevalence figure.  An additional table was developed using information from the 2004 BRFSS Prevalence Summary.  It includes information for the 50 states and the District of Columbia for a selected number of risk factors. For each measure shown, a rank of 1 indicates the negative end of the ranking.  For all measures, a low percent indicates the desired prevalence.

A further comparison of risk factors to national objectives is provided in Appendix A. These tables compare Indiana risk factor prevalences from BRFSS data with national objectives and national BRFSS prevalences for those behaviors for which Healthy People 2010 has explicitly stated objectives and that were measured in Indiana in 2004.