The study will assess the the burden of living with allergic rhinitis (AR) and the effect of AR on school performance for children and adolescents in Denmark.

The aim of the study is to investigate the effect of AR on school performance and examination test grades for children and adolescents diagnosed with AR early in life, as well as analyse their burden of disease and healthcare resource use using real-world data from the exhaustive Danish population registers. This is a retrospective registry analysis that uses Danish registers during 1994 and 2021.

In Denmark, national registers collect data for the entire Danish population from birth to death and have done so for decades. This exhaustive data creates a sound foundation for this study of the impact of school performance caused by AR, as subjects can be traced with high certainty and detail over several years.

Inclusion Criteria:

• The main study population (cases) consists of children who have been diagnosed with AR before turning 13. Diagnosis of AR will be identified by dispensations of prescribed AR medications, ICD-10 codes of AR-related hospitalisations and reimbursement codes for AR-related healthcare contacts in the primary healthcare sector.

At least two dispensed prescriptions of product containing intranasal corticosteroids (INCS) or antihistamines during the same calendar year for two consecutive years OR at least one visit with the primary healthcare sector with registered AR consultations AND at least one dispensed prescriptions of product containing INCS or antihistamines OR at least one contact with the hospital sector with an ICD-10 code for AR (primary or secondary diagnosis).

Exclusion Criteria:

• Children with their first AR-related healthcare contact or first AR-specific dispensed prescription at the age of 13 or older will be excluded.

children who have been diagnosed with AR before turning 13