Behavioral Risk Factor Surveillance System BRFSS

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Behavioral Risk Factor Surveillance System (BRFSS)

• Contributors Wayne A. Honey, MPH
• Jennifer E. Daniel, MPH
• Annie Hickman, BS
• Survey Unit, Injury Behavioral Epidemiology
  Bureau
• Epidemiology Response Division, NM Department
  of Health
• December 8, 2004

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BRFSS - Objectives

• Determine priority health issues populations at
  highest risk for illness, disability, and death.
• Support development of strategic plans
• Target prevention programs
• Educate the public, the health community, and
  policy makers about disease prevention.

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BRFSS - Objectives

• Support community policies that promote health
  and prevent disease.
• Monitor the effectiveness of interventions and
  progress in meeting prevention goals (limited).

4
BRFSS Applications (Examples on following
slides)

• Estimate Prevalence Distribution of Selected
  Diseases/Conditions
• Estimate Prevalence Distribution of Risk
  Behaviors Protective Factors
• Comparison to HP2000 HP2010
• Monitor Trends

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Binge Drinking 2003
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2003 NM BRFSS Healthy People 2010 Objs
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Monitor Trends
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Breast Cancer ScreeningNo Significant Difference
(Other than 1991 1997)All Female Respondents
Age 40, excluding DK/NS, Refused, or missing.
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Cervical Cancer ScreeningNo Significant
Difference (Other than 1997)Denominator includes
all female survey respondents age 18 and older
with uterine cervix except those with missing,
don't know, and refused answers.
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BRFSS Applications (Examples on following
slides)

• Describe Associations Between Disease/Conditions
  Risk Factors
• Estimate Prevalence of Health Care Coverage
• Comparisons State-to-State, State to Nation
  sub-state areas
• Estimate Utilization of Preventive Screening

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Associations
Prevalence of Chronic Health Conditions, by
disability status
100
No disability
Disability not requiring assistance
80
Disability requiring assistance
60
Percent of group with condition
40
20
0
Arthritis
Diabetes
Hypertension
Cardio-
Osteoporosis
(2000)
(1998-00)
(1999)
vascular
(1999)
disease
(1998,99)
Rates are age-adjusted by the direct method to
the weighted age distribution of the NM BRFSS
survey for the designated year or years.
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Comparisons State-to-State State-to-Region
State-to-Nation
Percentage of New Mexicans Without Health Care
Coverage
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Utilization of Preventive Screening
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Percentage of Women Not Screened for Breast CA.
New Mexico, Region, and U.S., 2000.
Region Arizona, Colorado, Utah, Oklahoma,
and Texas. 50 states, plus the District of
Columbia and Puerto Rico. Source U.S. BRFSS,
2000.
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Percentage of Women Age 40 and Older Who
HaveNever Had a Mammogram, by Education.
New Mexico, 2000.
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Percentage of Women Age 40 and Older Who Have
Never Had a Mammogram, by Household Income. New
Mexico, 2000.
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Percentage of Women Not Screened for Cervical CA.
New Mexico, Region, and U.S., 2000.
Region Arizona, Colorado, Utah, Oklahoma,
and Texas. 50 states, plus the District of
Columbia and Puerto Rico. Source U.S. BRFSS,
2000.
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Percentage of Women Who Never Had a Pap Smear,
by Household Income. New Mexico, 2000.
Household Income
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BRFSS - Methodology

• Telephone Survey Methods
• On going Survey of Adults
• Random Selection of Household
• Random Selection of One Adult (gt 18 Yrs.) Per
  Household
• Computer-Aided Telephone Interviewing (CATI)
  System

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Disproportionate Stratified Sample
Genesys, Inc. creates blocks of 100 s with same
area code, prefix, 2 digit suffix [phone]
thru [phone]
Compare to List of all possible s. Group into
following 2 Blocks
Listed s Sampled at 1.51 of Not-Listed 1
Block s
Not-listed 1 Block s
Zero Block Not sampled since 2002
Replicates of 50 Random s Each Replicate is a
Disproportionate Stratified Sample
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NM BRFSS Sample Geographic Stratification
Stratified since 2001 2004 Sample Size 6,430
Sample Per Stratum 1,286 DSS Design Replicated
in each stratum. 2004 6th
Stratum over-sampling Native Americans County
assignment to strata will change in 2006 to match
new Public Health Districts.
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Disproportionate Stratified Sample
Purchase lists of randomly generated
phone numbers from which known business
and non-working numbers have been eliminated
Dial one number
If no answer, redial up to 15 times.
If non-residence or non-working, stop.
If residence, determine eligibility
of household (at least one adult 18 or older).
If not eligible, stop
If eligible, randomly select one adult 18 or
older for the interview.
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BRFSS - Strengths

• State Sub-state Estimates
• State Control
• Timeliness
• Reasonable Reliability Validity (with
  caveats)
• Efficiency (Cost)
• Effective Monitoring of Data Collection

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BRFSS - Weaknesses

• Validity (Self-report)
• Reliability (Select Variables or small sample
  size)
• Refusal Rates higher than Face-to-Face, and
  Increasing
• Exclusion of non-telephone HH
• Exclusion of Cell Phones

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Accessing BRFSS Data

• Submit requests to wayne.honey_at_doh.state.nm.us
• Tables, charts, brief reports, or data files
• On-Line NM BRFSS Reports www.health.state.nm.us
  
• Click on Health Data tab
• Click on Health Behaviors
• Click on Adult
• Click on report of choice
• CDC BRFSS www.cdc.gov\brfss
• Click on Prevalence Data or Trends Data hot keys

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BRFSS - Weighting

• Probability of Selection
• FINALWT STRWT 1 OVER NPH NAD POSTSTRAT
• FINALWT is the final weight assigned to each
  respondent.
•  
• STRWT accounts for differences in the basic
  probability of selection among strata (subsets of
  area code/prefix combinations). It is the inverse
  of the sampling fraction of each stratum. There
  is seldom a complete correspondence between
  strata, which are defined by subsets of area
  code/prefix combinations, and regions, which are
  defined by the boundaries of government entities.

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BRFSS - Weighting

• Probability of Selection
• FINALWT STRWT 1 OVER NPH NAD POSTSTRAT
• 1/NPH is the inverse of the number of residential
  telephone numbers in the respondents household.
•  
• NAD is the number of adults in the respondents
  household.

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BRFSS - Weighting

• Probability of Selection
• FINALWT STRWT 1 OVER NPH NAD POSTSTRAT
• POSTSTRAT is the number of people in an
  age-by-sex or age-by-race/ethnicity-by-sex
  category in the population of a region or a state
  divided by the sum of the preceding weights for
  the respondents in the same age-by-sex or
  age-by-race/ethnicity-by-sex category.
• It adjusts for non-coverage and non-response
  and forces the sum of the weighted frequencies to
  equal population estimates for the region or
  state.