Objective: To perform a novel geographic analysis of Attention-Deficit/ Hyperactivity Disorder (ADHD) diagnosis in Midwest United States.
Method: Primary care children age 5-17 with ADHD diagnosis (N = 6833; 13.5%) were compared to those receiving well child care without ADHD diagnosis (N = 43,630) in a Wisconsin integrated medical system. Street addresses, demographic, and block group level U.S. Census 2000 data were mapped and analyzed using ArcGIS, CrimeStat III, and SaTScan. Lead levels from a State database were linked to 2,837 subjects. Univariate analysis was done by chi-square test or Mann-Whitney U test, multivariate analysis by logistic regression.
Results: ADHD cases were 74% male (p = 0.0001), and more frequently diagnosed in White children (17.3%) than Blacks (10.6%), Hispanics (9.4%), or Asians (3.7%; all p values < 0.001). Overall, male gender, white race, lower block group median household income and population density, and greater distance to nearest park and airport were more predictive of ADHD (p values < 0.001). In urban Milwaukee County (865 cases/10,493 controls) male gender, white race, suburban residence, and younger age were more predictive of ADHD (p values < 0.01). Among children with ADHD diagnosis and linked lifetime lead values, those with a maximum level of 10 microg/dl or more differed significantly from controls (9.3% vs. 5.6%; p = 0.003); elevated lead remained a significant predictor of ADHD diagnosis in multivariate analysis.
Conclusions: Further studies are needed to determine if geographic distribution of ADHD diagnosis can be partially explained by differential efficiency of referral for diagnosis by school districts, by race/ethnicity, and/or built environment.