Societal and personal financial burden of severe asthma and impact of biologic therapy: a 19-year nationwide cost analysis

Introduction Severe asthma incurs a financial burden on both patients and societies. However, little is known about the long-term financial burden and impact of biologic therapy. Methods All Danish adults initiating biologic therapy for severe asthma between 2016 and 2020 were included and followed retrospectively between 2002 and 2022, both prior to and during biologic therapy. Excess healthcare costs, foregone income and welfare transfers were calculated on an annual basis using a level of education-adjusted, zero-inflated generalised linear model with a gamma distribution and a log-link compared with age, sex, residence and civil status matched comparators. Results In total, 562 patients and 2207 comparators (median age 56 years, 51% female) were included. Excess healthcare costs during the year prior to biologic therapy were €10 590 and foregone income was €5389 per patient. The excess welfare transfers for patients aged 18–64 were €3335. Prior to biologic therapy, pooling of crude annual costs resulted in an accumulation of €59 364 and €44 155 in excess healthcare costs and foregone income per patient, respectively. Patients aged 18–64 had accumulated €32 021 in excess welfare transfers. Biologic therapy was associated with an increase in excess outpatient care costs (€25 938,+398.6%) compared with the year prior to biologic therapy. Outpatient care costs declined to (€14 486,+78.5%) during treatment year 4. Furthermore, at year 4, reductions in hospitalisations (€–2270, –67.7%) and patient-facing medication costs (€−557, –29.7%) compared with the year prior to biologic therapy were observed. Welfare transfers and foregone income were unaffected. Conclusions In the present study, patients with severe asthma initiating biologic therapy accumulated a substantial financial burden for both healthcare and welfare institutions, as well as a significant loss of personal income over time. Biologic therapy was associated with increased healthcare costs overall, but did not affect welfare transfers or foregone income.