Geographical variation in asthma prevalence within a state

Objectives: Examine the geography and correlates of asthma prevalence in school-aged children throughout our state using SAS^R and Geographic Information Software (ArcEditor^TM, Maptitude) based upon school level data. Design: New Jersey law enables children with a signed doctor's order to carry inhalers in school. NJ schools are required to have nurses; they are uniquely positioned to know how many students have asthma. In 2001, 2004, 2005, and 2007, school nurses were polled by a state-wide community health organization and asked how many students had asthma. Data were linked with annual school data from the National Center for Education Statistics' Common Core of Data and Private School Universe Survey. Sample: 1487 schools (40.5% of 3675 with at least one K-12 grade) responded 1 or more times representing 47.5% (783,199) of 1,650,327 students. Results: Asthma prevalence in NJ counties ranged from 6.5% to 11.2%, a nearly two-fold range. Several rural counties had unexpectedly high asthma prevalence. Mean prevalence overall was 8.4% (weighted by school size): 8.5% based on 1225 public schools, 7.9% based on 262 private schools. Study limitations will be discussed. School-level prevalence rate was positively correlated with % black students (r=.178, p<.0001), and negatively correlated with % Asian (r=-.149, p<.0001) and socioeconomic status, measured by % not receiving subsidized lunch (r=-.147, p<.0001). Prevalence clustered significantly (p<.01) according to the Moran's I statistic, both at the school level within counties and globally at the county level. Low-prevalence clusters were identified in some upper-class municipalities and high-prevalence clusters in some urban areas.