OBJECTIVES : To estimate the cost of illness of patients with moderate-to-severe atopic dermatitis (AD). In assessing the cost effectiveness of emerging biological therapies, it becomes increasingly important to establish the economic burden that patients with moderate-to-severe AD pose to the healthcare sector.

METHODS : The study cohort comprised Danish citizens with AD as a primary diagnosis determined by a dermatology department between 1997 and 2018, as identified in the Danish National Patient Register. The moderate-to-severe AD population where then identified via specific inclusion criteria on visits.

For each AD patient, we identified three controls through the Central Person Registry, matched on gender, birth year and region of residence in the index year (i.e. the year of first hospital contact regarding AD).

Actual direct costs for primary-sector visits and in- and outpatient hospitalisations were estimated for cases and controls in both the three years before and the five years after the index date.

RESULTS : The analysis included 5,666 patients with moderate or severe AD. We found that the average cost was significantly higher in the five years after the index date for cases vs. controls. In addition, the highest difference was found in the first year following the index date, with estimated total healthcare costs of EUR 4,973 for cases and EUR 1,515 for the matched controls (p<0.0001). We found that the increase was primarily driven by an increase in outpatient hospitalisations. Patients with moderate-to-severe AD had on average 10.6 outpatient hospitalisations in the year following the index date, resulting in a cost of EUR 3,059, whereas the matched controls on average had 1.3 outpatient hospitalisations in the same period, resulting in a cost of EUR 543 (p<0.0001).

CONCLUSIONS : This study provides population-based evidence of the substantial economic burden of moderate-to-severe AD compared to a group of matched controls.