Background Investigations in several Western countries have reported ethnic differences in asthma prevalence and treatment among children and in some countries these differences are increasing. The aim of this study was to analyse whether there are inequalities in asthma treatment by country of birth and ancestry among children residing in Denmark, and whether this potential association may vary between different household income groups.

Methods Data were obtained by linking the Danish Civil Registration System, the Central Taxpayers’ Register and the Danish National Prescription Register. Population: the entire population of children in Denmark from 0 to 17 years of age in 2008 (n=1 209 091). Information on asthma treatment was obtained from the National Prescription Register. The analyses included multiple logistic regression models stratified by household income.

Results Compared with ethnic Danes, immigrant children had the lowest OR for redeeming a prescription for asthma medication, both relief (OR 0.37; 95% CIs, 0.20 to 0.68) and preventive (OR 0.37; (0.22 to 0.59)). Similar associations were found among descendant children (OR for relief treatment 0.82 (0.79 to 0.89) and for preventive treatment 0.68 (0.61 to 0.75)). The pattern of the association remained after stratifying for household income.

Conclusions We found that, inequalities that cannot be explained by household income alone exist in treatments to prevent asthma as well as to relieve symptoms in children residing in Denmark, by country of birth and ancestry. The difference between immigrants and descendants may indicate that unfamiliarity with the Danish healthcare system is a contributory cause of the inadequate treatment of asthma.