Validate AA BRFSS Percents
Vitalnet produces age-adjusted mortality rates. So the mechanisms for doing age adjustment had already been working correctly. However, to be on the safe side, the age-adjusted BRFSS statistics within Vitalnet were validated by comparison with independently produced statistics. We were able to readily validate that the BRFSS AA statistics work correctly, despite the rarity of published BRFSS age-adjusted statistics.
Alaska - The Alaska BRFSS program is one of the few States that publishes age-adjusted statistics, in online PDF files. Alaska runs two BRFSS surveys. The second survey is called "Alaska Modified BRFSS" or "Alaska Supplemental BRFSS". From the 2008 Alaska BRFSS documentation:
"For some indicators BRFSS data were combined with data from a second survey, the Alaska Modified BRFSS. This survey was state developed and is funded by the Alaska Tobacco Prevention and Control Program and focuses largely on tobacco use and attitudes. The Modified BRFSS uses the same sample design, data collection methodology, and has the same sample size goal of 2,500 surveys collected per year as the BRFSS. Combining the Modified BRFSS survey with the BRFSS where possible allows for a larger sample size for analysis and more stable estimates. Also note that when the combined BRFSS and Modified BRFSS data were used, estimates will not match those provided by the CDC for those indicators."
So we chose those questions that were NOT asked on the Modified BRFSS, had results published in Alaska PDF to at least one decimal point, and were asked of all age groups. That left us with the following risk factors for the comparison, summarized here:
_CHOLCHK_______5YR_ - Had cholesterol check in past 5 years?
_FRTINDX_______GE5_ - Eats at least 5 fruits and vegetables a day?
HAVARTH_______EVER_ - Doctor made a diagnosis of arthritis?
_RFBINGE_______30D_ - Has recently been a binge drinker?
_RFCHOL_______EVER_ - Had cholesterol check and told high?
_RFDRHVY_______30D_ - Has recently been a heavy drinker?
VIGCAT_________NOW_ - Vigorous activity recommendations met?
A complication was that the Alaska age-adjusted rates used the following age distribution: 18-24, 25-34, 35-44, 45-64, 65+. This is distribution #9 from Klein and Schoenborn (2001). So for purposes of the validation / comparison, we built distribution #9 into Vitalnet software.
To increase the number of independent comparisons, analyses were also broken down by sex. As shown below, this resulted in a total of 16 comparisons. Each comparison exactly matched, with zero discrepancies.
| Question Code | Sex | Year | VB-QMS | AK PDF |
|---|---|---|---|---|
| BPHIGH_NP_____EVER_ | F | 2009 | 26.4 | 26.4 |
| BPHIGH_NP_____EVER_ | M | 2009 | 29.3 | 29.3 |
| _CHOLCHK_______5YR_ | F | 2009 | 74.0 | 74.0 |
| _CHOLCHK_______5YR_ | M | 2009 | 69.5 | 69.5 |
| _FRTINDX_______GE5_ | F | 2009 | 27.7 | 27.7 |
| _FRTINDX_______GE5_ | M | 2009 | 19.3 | 19.3 |
| HAVARTH_______EVER_ | F | 2009 | 27.6 | 27.6 |
| HAVARTH_______EVER_ | M | 2009 | 22.3 | 22.3 |
| _RFBINGE_______30D_ | F | 2009 | 12.3 | 12.3 |
| _RFBINGE_______30D_ | M | 2009 | 22.2 | 22.2 |
| _RFCHOL_______EVER_ | F | 2009 | 31.8 | 31.8 |
| _RFCHOL_______EVER_ | M | 2009 | 32.3 | 32.3 |
| _RFDRHVY_______30D_ | F | 2009 | 06.5 | 06.5 |
| _RFDRHVY_______30D_ | M | 2009 | 05.7 | 05.7 |
| VIGCAT_________NOW_ | F | 2009 | 32.6 | 32.6 |
| VIGCAT_________NOW_ | M | 2009 | 44.3 | 44.3 |
So this validates that VB-QMS BRFSS age-adjusted statistics work correctly.
Contact us if you have suggestions / comments, or to license Vitalnet BRFSS Query & Mapping Software to make better use of your data.