Background and aims
Studies examining ethnic and migrant differences in children’s medicine use are scarce. This thesis seeks to elucidate ethnic and migrant differences in use of medication for the most common health complaints and chronic conditions among children. It investigates the mediating role of potential explanations such as psychosocial stressors and socioeconomic characteristics of the household and the area of residence. Concretely, the aims are four:

1. To examine whether psychosocial stressors (not feeling safe at school) can explain migrant differences in medicine use for aches (Paper I)
2. To assess whether ethnic and migrant differences in medicine for aches are present across different ethnic minority groups (Paper II)
3. To examine whether household income explains ethnic and migrant differences in asthma medication among children (Paper III)
4. To examine whether area-based income level explains ethnic and migrant differences in asthma medication among children (Paper IV)
Methods
Questionnaire-based studies
The Health Behaviour in School-Aged Children survey was used to identify the study population, which included children, aged 11, 13 and 15 years old. Information on country of birth of child, country of birth of the parents, gender, age, symptoms and feeling safe at school for the study population was retrieved. The main statistical analysis was a multivariable, multilevel logistic analysis with probability for using medicines for aches (headache and stomach-ache) as outcome variable, and ethnic and migrant background as independent variable adjusted for demographic characteristics, symptoms and feeling safe at school.

Register-based studies
The Danish Civil Registration System was used to identify the study population, which included all children from ages 0 to 17 in 2008. Through registers operated by Statistics Denmark, information on country birth of child, country of birth of the parents, gender and age and income of the parents for the study population was retrieved. Information on out-patient prescription medication use was obtained from the National Prescription Register. The main statistical analysis was a multivariable, multilevel logistic analysis with probability of redeeming a prescription for asthma medication as outcome variable, and ethnic and migrant background as independent variable adjusted for demographic characteristics and stratified by household income or mediated by household or area-based income level.

Results
I found that ethnic and migrant background was associated with higher use of medicine for aches compared to the majority population for first generation immigrants as well as for descendants’ children (papers I and II). Low levels of feeling safe at school were associated with migrant background and with higher use of medicine for aches, but it only attenuated the association between migrant background and medicine use (paper I).

I found that ethnic and migrant background was associated with lower use of prescription medication for asthma compared to the majority population, and that a gradient between ethnic Danish children, descendants and immigrants was present. The household income stratified analysis showed that ethnic and migrant differences are present in the three strata, with the largest differences found for the low household income tertile (paper III). The multivariable, multilevel analysis showed that although significant, area-based income level did not account for differences in use of asthma medication (paper IV).

Conclusion
Ethnic and migrant differences are present in medicine use for aches as well as for asthma medication. However, the associations had different directions suggesting that medicine use behaviour among children is sensitive to the type of medication and the way the medication is obtained. The psychosocial stressors and socioeconomic factors chosen were significantly associated with medicine use but did not explain the associations. More in depth research is needed to understand medicine use behaviour among ethnic and migrant children and parents with focus on studying knowledge, perception and attitudes towards different types of medication.