PURPOSE: To determine whether sociodemographic factors are associated with 
delays at specific steps in the diagnostic process of Duchenne and Becker 
muscular dystrophy.
METHODS: We examined abstracted medical records for 540 males from 
population-based surveillance sites in Arizona, Colorado, Georgia, Iowa, and 
western New York. We used linear regressions to model the association of three 
sociodemographic characteristics with age at initial medical evaluation, first 
creatine kinase measurement, and earliest DNA analysis while controlling for 
changes in the diagnostic process over time. The analytical dataset included 375 
males with information on family history of Duchenne and Becker muscular 
dystrophy, neighborhood poverty levels, and race/ethnicity.
RESULTS: Black and Hispanic race/ethnicity predicted older ages at initial 
evaluation, creatine kinase measurement, and DNA testing (P < 0.05). A positive 
family history of Duchenne and Becker muscular dystrophy predicted younger ages 
at initial evaluation, creatine kinase measurement and DNA testing (P < 0.001). 
Higher neighborhood poverty was associated with earlier ages of evaluation (P < 
0.05).
CONCLUSIONS: Racial and ethnic disparities in the diagnostic process for 
Duchenne and Becker muscular dystrophy are evident even after adjustment for 
family history of Duchenne and Becker muscular dystrophy and changes in the 
diagnostic process over time. Black and Hispanic children are initially 
evaluated at older ages than white children, and the gap widens at later steps 
in the diagnostic process.