Community BMI Surveillance Using an Existing Immunization Registry in San Diego, California

This study examines the demographic representativeness of the County of San Diego Body Mass Index (BMI) Surveillance System to determine if the BMI estimates being obtained from this convenience sample of individuals who visited their healthcare provider for outpatient services can be generalized to the general population of San Diego. Height and weight were transmitted from electronic health records systems to the San Diego Immunization Registry (SDIR). Age, gender, and race/ethnicity of this sample are compared to general population estimates by sub-regional area (SRA) (n = 41) to account for regional demographic differences. A < 10% difference (calculated as the ratio of the differences between the frequencies of a sub-group in this sample and general population estimates obtained from the U.S. Census Bureau) was used to determine representativeness. In 2011, the sample consisted of 352,924 residents aged 2-100 years. The younger age groups (2-11, 12-17 years) and the oldest age group (≥65 years) were representative in 90, 75, and 85% of SRAs, respectively. Furthermore, at least one of the five racial/ethnic groups was represented in 71% of SRAs. This BMI Surveillance System was found to demographically represent some SRAs well, suggesting that this registry-based surveillance system may be useful in estimating and monitoring neighborhood-level BMI data.