Changes in oral corticosteroid use in asthma treatment-A 20-year Danish nationwide drug utilisation study.

Oral corticosteroids (OCS) are used in asthma management but can cause serious adverse effects. We aimed to investigate the usage trends in a nationwide asthma cohort in Denmark from 1999 to 2018. Using national registers, we identified young adults (18-45 years) with two or more asthma drug collections within 12 months since the age of 15 years as indicative of active asthma. OCS exposure level was stratified as high use (≥5 mg prednisolone/day/year) and low use (<5 mg/day/year). Lorenz curves were computed to illustrate potential skewness of consumption among the OCS users. We identified 318 950 individuals with a median age of 29 years (IQR 20-38 years) whereof 57% were women. The 1-year prevalence of OCS users was stable at 4.8% (median, IQR 4.7%-4.8%), but with nearly 40% decrease in high-users from 0.54% in 1999 to 0.33% in 2018. The median annual exposure decreased from 500 mg/year (1999) to 250 mg/year (2018). We found a substantial skewness in the distribution of OCS usage with 10% of users accounting for almost 50% of all OCS use. The prevalence of OCS users among young adults with active asthma has been relatively stable from 1999 to 2018, but with a decreasing prevalence of high-users and annual consumption.