Methods for Disability and Health Data System (DHDS)

Overview

Disability and Health Data System (DHDS) contains data on disability status and types, demographics, and health topics for the United States, the District of Columbia, and select U.S. territories. The methodology for calculating these estimates is specific to DHDS and might not be applicable outside of this system. Therefore, estimates in DHDS may not match those reported in other Centers for Disease Control and Prevention (CDC) data systems and reports.

View the Data Guides for a list of indicators and their definitions. The data guides provide detailed information for each indicator, including

• Definitions of indicators.
• Specific analysis criteria.
• Years for which the data are available.
• Citations if the definition was based on a publication.

Data source

The Behavioral Risk Factor Surveillance System (BRFSS) collects data through state-based telephone health surveys of civilian, non-institutionalized adults 18 years of age and older. All 50 states, the District of Columbia, Puerto Rico, Guam, and the U.S. Virgin Islands conduct the survey.

With assistance from CDC, trained interviewers collect comprehensive demographic, health condition, health risk behavior, and preventive health data. Get detailed information about BRFSS, including BRFSS questionnaires, codebooks, and methodology information.

Statistical analysis

Researchers used SAS (SAS Institute, Inc., Cary, North Carolina) and SAS-callable SUDAAN (Research Triangle Institute, Research Triangle Park, North Carolina) to perform analyses, accounting for the BRFSS complex survey design. Researchers calculated prevalence estimates, corresponding 95% confidence intervals (95% CI), and weighted numbers. Researchers weighted all estimates to account for

• Selection probability.
• Nonresponse.
• Noncoverage of households without telephones.
• Number of adults in a household.
• Number of telephones in a household.
• Population totals for each state or territory.

Most estimates were age-adjusted to the 2000 U.S. standard population, with the exception of estimates stratified by age.A For each indicator, researchers set "Don't know" and "Not sure" responses to missing. Researchers excluded respondents with missing data for an indicator from analyses involving that indicator. Researchers suppressed estimates if

• The standard error was greater than or equal to 30% of the estimate.
• The unweighted total population was less than 50.
• The standard error equaled 0.

Data are available for all 50 states, the District of Columbia, Puerto Rico, Guam, and the U.S. Virgin Islands. Data were also combined to produce estimates for the 10 U.S. Department of Health and Human Services regions,B and the U.S. and Territories combined.

Estimates

Disability estimates

Researchers calculated the prevalence of disability status and select disability types (cognitive, hearing, mobility, vision, self-care, and independent living) among adults overall and across the following demographic characteristics:

• Age
• Sex
• Race/ethnicity
• Veteran status

Demographics

Researchers analyzed demographic indicators (income level, education level, marital status, and employment status) in DHDS by disability status and types. They presented prevalence estimates for adults with and without any disability, as well as for six select disability types:

1. Cognitive
2. Hearing
3. Mobility
4. Vision
5. Self-care
6. Independent living

Health topics

DHDS displays health topic indicators in the following categories:

• Health Risks & Behaviors
• Prevention & Screenings
• Barriers & Costs of Health Care
• General Health Conditions
• Chronic Conditions
• Mental & Emotional Health

Researchers analyzed health topic indicators by disability status and types. They presented prevalence estimates for adults with and without any disability and by four select disability types:

1. Cognitive
2. Hearing
3. Mobility
4. Vision

Researchers also analyzed health topic indicators by disability status and three demographic groups. These analyses present prevalence estimates among adults with and without any disability, and additionally by

• Age groups (18–44, 45–64, and 65+ years).A
• Sex (male, female).
• Race/ethnicity (white, black, Hispanic, other/multiracial).C

Data limitations

The estimates presented in DHDS have several limitations:

1. BRFSS conducts a telephone survey that may result in higher non-coverage levels than in-person interviews. Some households are unreachable by phone.
2. Respondents self-report BRFSS data, which may be subject to recall bias and may be less accurate than data based on physical measurements like height, weight, and blood pressure.
3. BRFSS excludes people living in institutions or group homes. Since people living in these facilities may be more likely to have a disability, the survey may underestimate the prevalence of disability.
4. The BRFSS questions used to define disability do not include information on permanence, duration, or underlying medical conditions.