Utilization Patterns of Systemic Immunomodulating Drugs in Patients with Atopic Dermatitis in Clinical Practice

Background: In 2017, dupilumab was the first systemic drug approved for the treatment of adults with atopic dermatitis (AD) in the US. Its utilization, in the context of off-label systemic AD medication use, is unknown.

Objectives: We sought to describe patterns of prescribing, switching and discontinuing systemic drugs used for AD treatment, before and after the approval of dupilumab. We also sought to compare predictors of dupilumab prescription in the year dupilumab was approved and 2 years after.

Methods: Using longitudinal claims data from commercially insured patients in the US, we identified patients ≥ 18 years, who had a diagnosis of AD and filled a prescription for a topical therapy. Patients entered the cohort if they initiated a systemic therapy (dupilumab, cyclosporine, methotrexate, azathioprine, mycophenolate mofetil) from March 2015 to February 2021, not having used any study drug during 1 year before. For this utilization analysis, we required continuous enrollment in the database for 1 year before and after cohort entry. We excluded patients who had any condition with indications for treatment with any of the study drugs. We calculated proportion of patients taking each medication at 3, 6 and 12 months and used Sankey plots to describe persistence of use. We used logistic regression to determine predictors of dupilumab prescription.

Results: The number of patients with AD who started a systemic treatment was 319 in 2015-16 (before dupilumab approval) and 1358 in 2019-20 (after dupilumab approval). Methotrexate was the most common drug used in 2015-2016 (37.3%). Dupilumab use has surpassed all conventional drug use since its introduction in 2017 until the end of the study period in 2020-21 (71.6 to 83.7%). The proportion of patients discontinuing all systemic therapy at 1 year after initiating a systemic medication decreased from 62.4% in 2015-16 to 36% in 2019-2020. The age at which a systemic treatment for AD was initiated decreased from 58 years in 2015-16 to 49 years in 2019-2020. We found that 91.8% of patients who initiated dupilumab in 2020-21 had received no other systemic treatment before starting dupilumab. In 2017-18, meaningful predictors of dupilumab prescription were age < 60, asthma, use of steroid-sparing topical therapy and not using systemic glucocorticoids prior. In 2019-20, comorbid allergies were also a meaningful predictor while asthma was not.

Conclusions: Among incident users of a systemic treatment for AD, the proportion of those who started dupilumab was high. Patients who used steroid-sparing topical treatments were more likely to receive dupilumab than other off-label systemic agents.