Geographic analysis of diagnosis of Attention-Deficit/Hyperactivity Disorder in children: Eastern Wisconsin, USA.

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.