Drug Utilization and Medication Adherence: A Data-Driven Analysis of Drugs with Different Routes of Administration Applied in Atopic Dermatitis

Background: Medication adherence is one of the critical factors in optimizing treatment outcomes for chronic diseases such as atopic dermatitis (AD). Existing studies use aggregate data, but there is a need for assessment of medication adherence phases, such as the initiation and discontinuation of therapy. The aim of this study was to assess medication adherence across patients with moderate to severe AD, investigating the impact of drug treatment characteristics, particularly the route of administration, on adherence levels during treatment. Methods: A retrospective observational study on an Italian sample included 821 newly diagnosed AD patients from January 2021 to June 2022. Medication adherence was evaluated by EMERGE guidelines, focusing on initiation and discontinuation. Discontinuation was assessed at 6 and 12 months, comprising sensitivity analysis. Statistical analysis included chi-square tests and descriptive statistics on treatment duration. Results: Treatment initiation is significantly lower for tacrolimus ointment (38% non-initiation) than for dupilumab injection (12% non-initiation), due to initial healthcare support for dupilumab patients. After six months, 75.6% of dupilumab injection patients remained on therapy, while 24.4% of patients continued tacrolimus ointment treatment. After one year, therapy persistence was 68.7% among users of dupilumab, while only 22.5% of patients remained on tacrolimus therapy. Dupilumab demonstrated a significantly longer median treatment duration compared to tacrolimus (4.4 vs. 2.6 months; p < 0.01). Conclusions: The observed differences in adherence patterns between topical tacrolimus and subcutaneous dupilumab suggest that distinct contextual and behavioral factors influence patient adherence during therapy.