Tracking chronic disease and risk behavior prevalence as survey participation declines: statistics from the...

Response rates for the Behavioral Risk Factor Surveillance System (BRFSS) have declined in recent years. The response rate in 1993 was approximately 72%; in 2006, the response rate was approximately 51%. To assess the impact of this decline on the quality of BRFSS estimates, we compared selected health and risk factor estimates from BRFSS with similar estimates from the National Health Interview Survey (NHIS) and the National Health and Nutrition Examination Survey (NHANES).

We reviewed questionnaires from the 3 surveys and identified a set of comparable measures related to smoking prevalence, alcohol consumption, medical conditions, vaccination, health status, insurance coverage, cost barriers to medical care, testing for human immunodeficiency virus, and body measurements (height and weight). We compared weighted estimates for up to 15 outcome measures, including overall measures and measures for 12 population subgroups. We produced design-appropriate point estimates and carried out statistical tests of hypotheses on the equality of such estimates. We then calculated P values for comparisons of NHIS and NHANES estimates with their BRFSS counterparts.

Although BRFSS and NHIS estimates were statistically similar for 5 of the 15 measures examined, BRFSS and NHANES estimates were statistically similar for only 1 of 6 measures. The observed differences for some of these comparisons were small, however.

These surveys produced similar estimates for several outcome measures, although we observed significant differences as well. Many of the observed differences may have limited consequences for implementing related public health programs; other differences may require more detailed examination. In general, the range of BRFSS estimates examined here tends to parallel those from NHIS and NHANES, both of which have higher rates of participation.