Behavioral Risk Factors Surveillance System

BRFSS at a Glance

Behavioral Risk Factors Surveillance System
Data Type Self-report survey
Sample Nationally, State representative Sample
VEHSS Topics Included Visual Function
Years Analyzed 2016
Approximate Size 400,000 people per year

The Behavioral Risk Factor Surveillance System (BRFSS) is the nation’s premier system of health-related telephone surveys that collect state data about US residents regarding their health-related risk behaviors, chronic health conditions, and preventive services use. Established in 1984 with 15 states, BRFSS now collects data in all 50 states as well as the District of Columbia and three US territories. BRFSS completes more than 400,000 adult interviews each year, making it the largest continuously conducted health survey system in the world. The survey is administered by the CDC’s Division of Population Health in the National Center for Chronic Disease Prevention and Health Promotion.

Sample Design:

Home telephone numbers are obtained through random-digit dialing. The inclusion of data from cellular telephone interviews in the BRFSS public release data set has been standard protocol since 2011. Adults 18 years or older are asked to take part in the survey. The number of interviews within each state will vary on the basis of funding and the size of regions, such as health districts, within each state.

Data Collection Procedures:

As of 2015, data are collected monthly. With technical and methodological assistance from the CDC, state health departments use in-house interviewers or contract with telephone call centers or universities to administer the BRFSS surveys continuously through the year. The states use a standardized core questionnaire, optional modules, and state-added questions. In 2014, 50 states, the District of Columbia, Guam, and Puerto Rico collected samples of interviews conducted both by landline telephone and cellular telephone.

Behavioral Risk Factors Surveillance System

Behavioral Risk Factors Surveillance System

sample spreadsheet

Behavioral Risk Factors Surveillance System

Analysis Overview

For the VEHSS team, CDC estimated the prevalence rate and sample size for each survey instrument selected for inclusion. We analyzed the 2014 and 2015 BRFSS files separately. The prevalence rate was defined as the number of persons who gave an affirmative response to the question divided by the total number of respondents who gave an affirmative or negative response and multiplied by 100 for presentation in percentage format.  We estimated upper and lower confidence intervals and the relative standard error (RSE) of the prevalence estimate using the Clopper-Pearson method.[1] Estimates that were based on a sample size of less than 30 and/or with a relative standard error greater than 30% were suppressed.

A detailed description of the analytical steps is described in the report “VEHSS Survey Analysis Plan Cdc-pdf[PDF – 480 KB]External.”

Variables Analyzed in VEHSS:

During the selected years 2014–2015 BRFSS contains a single question relevant to VEHSS: “Is this person blind or does he/she have serious difficulty seeing even when wearing glasses?” This question, was categorized under the VEHSS ‘Visual Function’ topic and ‘Difficulty Seeing with Glasses’ category. The table below presents additional details about the question, including the BRFSS variable name, the year(s) survey data are available, the survey question, and the response options.

Overview of BRFSS Variables included in VEHSS

VEHSS Indicator Topic VEHSS Indicator Category BRFSS Variable Name BRFSS Question Text Years Available (analyzed) Response Options
Visual Function Difficulty Seeing with Glasses BLIND Are you blind or do you have serious difficulty seeing, even when wearing glasses? 2013–2016
    • 1 Yes
    • 2 No
    • 3 Not applicable (blind)
    • 7 Don’t know/Not sure
    • 9 Refused

Additional information about BRFSS can be found on the CDC website.

[1] Parker JD, Talih M, Malec DJ, et al. National Center for Health Statistics data presentation standards for proportions.  Vital Health Stat. 2017;2(175).