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Technical Notes 2019

Behavioral Risk Factor Surveillance System (BRFSS)

The Behavioral Risk Factor Surveillance System (BRFSS) surveys noninitialized adults about their health behaviors, conditions and practices. The State Center for Health Statistics (SCHS) publishes detailed prevalence estimates from each year’s North Carolina BRFSS. We produce tables of prevalence estimates for most variables of substantive interest in each year’s survey. Prevalence tables cover the state as well as several sub-state regions described below. This document provides an overview of these tables, notes on the BRFSS survey methodology, and definitions for selected variables and regions.

Overview of Prevalence Tables

Most table titles use exact wording from each survey question. Due to space limitations, titles may not include some introductory remarks and explanations for some questions. The full questionnaire may be viewed online. Some tables report results for “calculated variables,” variables that are computed from answers to more than one survey question. For example, “current smoker” is derived from the first two questions in the tobacco use section. Readers should consult the table footnotes for definitions of calculated variables.

Results for most survey items are displayed by gender, race/ethnicity, age, education, and other sociodemographic variables. We report the number of respondents, weighted percentage estimates, and 95-percent confidence intervals for each percentage. Since weighted data are used in all calculations, percentages shown in web tables cannot be derived exactly from the number of respondents reported in each cell of the table.

Respondents who refused to answer or did not know the answer are excluded from most calculations in these tables. We include "Don't know/Not sure" responses in instances when they provide valuable information.

BRFSS data are weighted for the probability of selection of a telephone number, the number of adults in a household, the number of phones in a household, and then adjusted to reflect the demographic distribution of North Carolina's adult population (ages 18 and older).

In 2011, a new weighting methodology called iterative proportional fitting (or “raking”)i replaced the post-stratification method to adjust BRFSS data to reflect the state’s population. Raking allows incorporation of cellular telephone survey data and permits the introduction of additional demographic characteristics (e.g., education level, marital status, home renter/owner) in addition to age-race/ethnicity-gender. Adding these variables to the weighting process improves the degree and extent to which the BRFSS sample reflects the socio-demographic make-up of individual state. The 2019 BRFSS raking method includes categories of age by gender, detailed race and ethnicity groups, education levels, marital status, regions within states, gender by race and ethnicity, telephone source, renter or owner status, and age groups by race and ethnicity.

The SCHS suppresses prevalence estimates which do not meet minimal criteria for statistical reliability. In our 2019 tables, we suppress prevalence estimates when any of the following criteria are met:

  1. There are fewer than 10 respondents in the numerator (i.e. the number of respondents associated with the response categories, e.g. “Yes-No”).
  2. There are fewer than 50 respondents in the denominator (i.e. the total number of respondents to a question).
  3. The width of the confidence interval for the prevalence estimate is greater than 20.
  4. Cases where a table cell estimate has a relative standard error of greater than 30 percent. The relative standard error is a measure of a statistical estimate's reliability obtained by dividing the standard error by the estimate; then multiplied by 100 to be expressed as a percentage.

Geographic Areas Covered

We publish four sets of tables showing prevalence estimates for the full North Carolina non-institutionalized adult population.

  • North Carolina Statewide,
  • North Carolina statewide by gender,
  • North Carolina statewide by race,
  • North Carolina statewide by risks, conditions, and quality of life.

We publish results for the following sub-state areas:

  • North Carolina Association of Local Health Directors regions,
  • North Carolina Medicaid Managed Care regions,
  • Area Health Education Centers (AHEC) regions, and
  • three broad regions of the state (Eastern North Carolina, Piedmont, and Western North Carolina).

A list of the counties in each of these regional groupings is shown at the end of this document.

NOTE: The North Carolina BRFSS does not produce county-level prevalence estimates. We understand the desire for county-level BRFSS estimates. Unfortunately, we are simply not able to provide them given the current survey design.

To produce county estimates, we would need to stratify our sampling frame by county. Stratification relies on knowing where the phone number is located when the sample is drawn (prior to the interview). This information is available for landline phone numbers, but not for cell phone numbers. There is currently no reliable way to stratify a cell phone sample to the county level. The best we can do are the groupings of counties that make up the North Carolina Association of Local Health Director regions.

Currently around 80 percent of our interviews are done with persons reached on a cell phone. County estimates using only landline numbers would be seriously biased, as there would be too few respondents who are young, minority, or lower socio-economic-status. In our 2019 data, for example, less than four percent of respondents reached on a landline were under 35 years old, 72 percent were Non-Hispanic whites, and 63 percent were women.

BRFSS Survey Methodology

The BRFSS is designed to estimate characteristics of the non-institutionalized adult population, that is people 18 year of age or older who are not inmates of institutions (penal, mental facilities, homes for the aged). A dual frame landline and cellular phone telephone sample was generated by Marketing Systems Group (MSG) using Random Digit Dialing procedures. Live interviewers called landlines and cellular phone numbers. For landline phones, one adult resident was randomly selected to complete the interview. Cellular phones were treated as individual devices and the interview is conducted with the adult answering the phone. Our 2019 sample included 824 interviews completed on landlines and 3,463 interviews completed via cellular phones.

BRFSS Response rates are calculated using the American Association of Public Opinion Research (AAPOR) Response Rate Formula #4.ii The response rate is the number of respondents who completed the survey as a proportion of all eligible and likely-eligible persons.

In 2019, North Carolina’s landline response rate was 41.1 percent, while the cell phone response rate was 40.6 percent. Our 2019 combined landline and cell response rate was 40.8 percent.iii

Definitions of Selected Calculated Variables

As noted earlier, “calculated variables” are computed from answers to more than one survey question or draw on other information. Definitions for most calculated variables are given in footnotes to tables where they are used. Below we provide definitions for more complex calculated variables.

Functional Disability

The BRFSS includes all six questions recommended by the U.S. Department of Health and Human Services as the national standard for identifying disabilities in population-based health surveys.iv The questions (8.20 through 8.25 in the 2019 questionnaire) ask whether the respondent has serious difficulty with several domains of functioning. Respondents who answered “yes” to at least one of these questions is defined as having a functional disability. Those who answered “no” to all six questions have no functional disability.

Poverty Level

This is a rough measure of how the respondent’s household income compares to the 2019 poverty guidelines established by the U.S. Department of Health and Human Services. The respondent’s income (the mean of the income category they choose in question 8.16) is divided by the poverty level income for their household size, then converted to a percentage. The result expresses the respondent’s household income as a percentage of poverty income. In 2019, poverty level income for a single-person household was $12,490. A respondent living alone whose income was $12,490 would be at “100% poverty.” If their income was $24,980, they would be at “200% poverty.” This continuous poverty level variable is categorized for reporting.

Please contact the BRFSS Staff if you have questions about this measure or would like a copy of the SAS code used to create the variable.

Rural-Urban Resident

Respondent’s county of residence is coded as rural, suburban or urban counties based on the North Carolina Rural Center’s county classification. For 2019, Durham, Forsyth, Guilford, Mecklenburg, New Hanover, and Wake were classified as urban counties. Alamance, Buncombe, Cabarrus, Catawba, Cumberland, Davidson, Gaston, Henderson, Iredell, Johnston, Lincoln, Onslow, Orange, Pitt, Rowan, and Union were classified as suburban or regional city counties. The remaining counties are classified as rural.

North Carolina Department of Commerce County Tier

Respondent’s county of residence is coded into one of the N.C. Department of Commerce 2019 Development Tier Designations. The tiers measure economic well-being based on unemployment, median household income, population growth, and property tax base.

Body Mass Index Grouping

Body mass index (BMI) is computed as weight in kilograms divided by height in meters squared:(kg/ m2). BMI is an intermediate variable used in calculating these measures:
Underweight: BMI less than 18.5, Recommended Range: BMI 18.5 to 24.9, Overweight: BMI 25.0 to 29.9, Obese: BMI greater than 29.9. and Overweight or Obese: BMI greater than 24.9.

Health Insurance Coverage - Age Under 65

Yes: All respondents less than age 65 who answered YES to the Core question on having any kind of health (HLTHPLN1). Respondents with missing age were excluded.
No: All respondents less than age 65 who answered NO to the Core question on having any kind of health (HLTHPLN1). Respondents with missing age were excluded.

Health Insurance Coverage for Those Employed for Wages (Age under 65)

Yes: All respondents less than age 65 who answered YES to the Core question on having any kind of health (HLTHPLN1), and answered “yes” to being employed for wages. Respondents with missing age were excluded.
No: All respondents less than age 65 who answered YES to the Core question on having any kind of health (HLTHPLN1), and answered something OTHER then “yes” to being employed for wages. Respondents with missing age were excluded.

Smoking Status

Current Smoker (every day): Respondents who have smoked at least 100 cigarettes in their lifetime and now smoke every day.
Current Smoker (some days): Respondents who have smoked at least 100 cigarettes in their lifetime and now smoke some days.
Former Smoker: Respondents who have smoked at least 100 cigarettes in their lifetime and currently do not smoke.
Never Smoked: Respondents who have not smoked at least 100 cigarettes in their lifetime.

Current Smoker

Yes: Current Smoker (every day or some days)
No: Former Smoker or Never Smoked.

Number of Pack Years. The average of number of 20-cigarette packs smoked per day multiplied by the number of years smoked.

Binge Drinking

No : Respondents who report they did not drink in the past 30 days, or who drank in the past 30 days but did not have five or more drinks for males or four or more drinks for females on an occasion.
Yes : Respondents who report they did drink in the past 30 days and had five or more drinks for males or four or more drinks for females on one or more occasions in the past month.

Heavy Drinking

Yes: Respondents reported having MORE than 2 drinks/day for MALES and MORE than 1 drink/day for FEMALES.
No: Respondents reported having LESS than or equal to 2 drinks/day for MALES and LESS than or equal to 1 drink/day for FEMALES.

Moderate Drinking Guidelines

Males having a maximum of two drinks on one or more occasions within the past 30 days or females having a maximum of one drink on one or more occasions within the past 30 days are considered to have met the CDC Guidelines for moderate drinking.

Excessive Drinking

Yes: Respondents who said they had drank in the past 30 days and had at least one binge drinking episode (5 or more drinks on one occasion for men 4 or more drinks for women)
or were heavy drinkers (2 or more drinks per day for men, more than 1 drink per day for women).

No: Respondents who said they did not drink in the past 30 days or who were not heavy drinkers and had no binge drinking episodes.

Family Planning Calculated Variables

Several variables relating to family planning practices are derived from the three questions in Optional Module 23 on Family Planning. These questions were only asked of women aged 18 to 49.

Women at Risk for Unintended Pregnancy. Women who are sexually active with a male partner, not pregnant or trying to get pregnant, and capable of becoming pregnant in the absence of using contraception are considered to be at risk. The remaining women are coded as not at risk.

Women in Need of Contraceptive Services. This variable is very similar to “at risk for unintended pregnancy.” It excludes women who have chosen surgical sterilization as a means of contraception.

Effectiveness of Current Contraceptive Method. This variable classifies the contraceptive method identified in questions 2 and 3 as highly, moderately, or least effective as described below.

  • Highly effective methods include male or female sterilization, contraceptive implants, or IUDs.
  • Moderately effective methods include shots such as Depo-Provera, birth control pills, contraceptive patches, contraceptive rings, or diaphragms.
  • Least effective methods include condoms, rhythm method, withdrawal, contraceptive foams, jelly or creams, cervical cap, sponges, or emergency contraception (morning after pill).

Respondents who were sexually active with a male partner and capable of getting pregnant but used none of the above contraceptive methods were codes as using no contraceptive method.

Used Long-Acting Reversible Contraceptive (LARC) Method. Respondents who were sexually active with a male partner, capable of getting pregnant who used a contraceptive implant or IUD are coded as “Yes, used a LARC.” Those using any other contraceptive method are coded as not using a LARC.

Please contact the BRFSS Staff if you have questions about these measures or would like a copy of the SAS code used to create them.

Definition of Regions

North Carolina Association of Local Health Directors Regions

Regions 1 & 2: Avery, Buncombe, Burke, Caldwell, Cherokee, Clay, Graham, Haywood, Henderson, Jackson, Macon, Madison, McDowell, Mitchell, Polk, Rutherford, Swain, Transylvania, and Yancey counties.

Region 3: : Alleghany, Ashe, Davidson, Davie, Forsyth, Stokes, Surry, Watauga, Wilkes, and Yadkin counties.

Region 4: Alexander, Cabarrus, Catawba, Cleveland, Gaston, Iredell, Lincoln, Mecklenburg, Rowan, Stanly, and Union counties.

Region 5: Alamance, Caswell, Chatham, Durham, Guilford, Orange, Person, Randolph, and Rockingham counties.

Region 6:Anson, Cumberland, Harnett, Hoke, Lee, Montgomery, Moore, Richmond, and Scotland counties.

Region 7: Edgecombe, Franklin, Granville, Halifax, Johnston, Nash, Vance, Wake, Warren, and Wilson counties.

Region 8: Bladen, Brunswick, Columbus, Duplin, New Hanover, Onslow, Pender, Robeson, and Sampson counties.

Regions 9 & 10: Beaufort, Bertie, Camden, Carteret, Chowan, Craven, Currituck, Dare, Gates, Greene, Hertford, Hyde, Jones, Lenoir, Martin, Northampton, Pamlico, Pasquotank, Perquimans, Pitt, Tyrell, Washington, and Wayne counties.

State Regions

Eastern NC: Beaufort, Bertie, Bladen, Brunswick, Camden, Carteret, Chowan, Columbus, Craven, Cumberland, Currituck, Dare, Duplin, Edgecombe, Gates, Greene, Halifax, Harnett, Hertford, Hoke, Hyde, Johnston, Jones, Lenoir, Martin, Nash, New Hanover, Northampton, Onslow, Pamlico, Pasquotank, Pender, Perquimans, Pitt, Robeson, Sampson, Scotland, Tyrrell, Washington, Wayne, and Wilson counties.

Piedmont: Alamance, Alexander, Anson, Cabarrus, Caswell, Catawba, Chatham, Cleveland, Davidson, Davie, Durham, Forsyth, Franklin, Gaston, Granville, Guilford, Iredell, Lee, Lincoln, Mecklenburg, Montgomery, Moore, Orange, Person, Randolph, Richmond, Rockingham, Rowan, Stanly, Stokes, Union, Vance, Wake, Warren, and Yadkin counties.

Western NC: Alleghany, Ashe, Avery, Buncombe, Burke, Caldwell, Cherokee, Clay, Graham, Haywood, Henderson, Jackson, McDowell, Macon, Madison, Mitchell, Polk, Rutherford, Surry, Swain, Transylvania, Watauga, Wilkes, and Yancey counties.

Area Health Education Centers (AHEC)

Mountain AHEC: Buncombe, Cherokee, Clay, Graham, Haywood, Henderson, Jackson, Macon, Madison, McDowell, Mitchell, Polk, Rutherford, Swain, Transylvania, and Yancey counties.

Northwest: Alexander, Alleghany, Ashe, Avery, Burke, Caldwell, Catawba, Davidson, Davie, Forsyth, Iredell, Rowan, Stokes, Surry, Watauga, Wilkes, and Yadkin counties.

Charlotte: Anson, Cabarrus, Cleveland, Gaston, Lincoln, Mecklenburg, Stanly, and Union counties.

Greensboro: Alamance, Caswell, Chatham, Guilford, Montgomery, Orange, Randolph, and Rockingham counties.

Southern Regional: Bladen, Cumberland, Harnett, Hoke, Moore, Richmond, Robeson, Sampson, and Scotland counties.

Southeast: Brunswick, Columbus, Duplin, New Hanover, and Pender counties.

Wake: Durham, Franklin, Granville, Johnston, Lee, Person, Vance, Wake, and Warren counties.

Area L & Eastern: Beaufort, Bertie, Camden, Carteret, Chowan, Craven, Currituck, Dare, Edgecombe, Gates, Greene, Halifax, Hertford, Hyde, Jones, Lenoir, Martin, Nash, Northampton, Onslow, Pamlico, Pasquotank, Perquimans, Pitt, Tyrrell, Washington, Wayne, and Wilson counties.

North Carolina Medicaid Managed Care Regions

Region 1: Avery, Buncombe, Burke, Caldwell, Cherokee, Clay, Graham, Haywood, Henderson, Jackson, McDowell, Macon, Madison, Mitchell, Polk, Rutherford, Swain, Transylvania, and Yancey counties.

Region 2: Alleghany, Ashe. Davidson, Davie, Forsyth, Guilford, Randolph, Rockingham, Stokes, Surry, Watauga, Wilkes, and Yadkin counties.

Region 3: Alexander, Anson, Cabarrus, Catawba, Cleveland, Gaston, Iredell, Lincoln, Mecklenburg, Rowan, Stanly, and Union counties.

Region 4: Alamance, Caswell, Chatham, Durham, Franklin, Granville, Johnston, Nash, Orange, Person, Vance, Wake, Warren, and Wilson counties.

Region 5: Bladen, Brunswick, Columbus, Cumberland, Harnett, Hoke, Lee, Montgomery, Moore, New Hanover, Pender, Richmond, Robeson, Sampson, and Scotland counties.

Region 6: Beaufort, Bertie, Camden, Carteret, Chowan, Craven, Currituck, Dare, Duplin, Edgecombe, Gates, Greene, Halifax, Hertford, Hyde, Jones, Lenoir, Martin, Northampton, Onslow, Pamlico, Pasquotank, Perquimans, Pitt, Tyrrell, Washington, and Wayne counties.

 

iMichael P Battaglia, Martin R. Frankel, and Michael Link. Improving Standard Poststratification Techniques for Random-Digit-Dialing Telephone Surveys. Survey Research Methods. 2008;2(1):11-19.

iiSee https://www.aapor.org/Standards-Ethics/Standard-Definitions-(1).aspx for details.

iiiThe combined response rate is the sum of each frame’s response rate multiplied the proportion of the total sample contributed by the frame.

ivBased on section 4302 of the Affordable Care Act, the Department of Health and Human Services issued data collection standard guidance to include a standard set of disability identifiers in all national population health surveys (https://aspe.hhs.gov/datacncl/standards/aca/4302/index.pdf).

Return to 2019 BRFSS Annual Results Table of Contents