The definition of response and inadequate response to topical corticosteroid treatment in atopic dermatitis and related skin inflammatory diseases: A GA2LEN ADCARE statement paper

Background: Topical corticosteroids (TCS) remain the first-line treatment for atopic dermatitis (AD) and related inflammatory skin diseases, yet no standardized definition of response exists. This gap contributes to heterogeneity in clinical practice and complicates trial design. We therefore aimed to develop consensus-based definitions of response and inadequate response to TCS therapy through a structured international eDelphi process. Methods: A PubMed search (1974-July 2025) identified 403 relevant publications. Candidate statements were drafted from the evidence and refined by the ADCARE Steering Committee, categorized into 3 domains (status quo, unmet need, proposals), and evaluated in a three-round eDelphi survey among certified ADCARE members. Eighty-four dermatologists and allergists from 32 countries participated (Round 1 response rate 98%; Round 2, 80%; Round 3, 76%). Statements were rated on a 5-point Likert scale; consensus was defined as ≥75% agreement (scores 4 or 5). Results: In total, 66 of 83 statements reached consensus. In the status quo domain, agreement centred on baseline severity, body surface area, and anatomical site as guiding factors for TCS choice, with potency and licensed duration considered central to safe prescribing. In the unmet-need domain, experts highlighted the absence of standardized definitions, variability in monitoring and escalation strategies, and gaps in long-term evidence and integration of patient-reported outcomes. In the proposal domain, consensus supported relative improvement thresholds (≥50% in EASI, SCORAD, itch NRS, IGA, PGA, POEM) and 14 days as a meaningful evaluation point. Absolute cut-offs, very short (7 days) or long (3 months) timeframes, and rigid escalation rules did not achieve consensus. These parameters were synthesized into concise and extended definitions of TCS response and inadequate response. Conclusions: LEN ADCARE initiative represents the first international consensus on defining TCS response and inadequate response, offering a framework to harmonize clinical practice, enhance trial comparability, and support guideline development.