Evaluating patient-perceived control of atopic dermatitis: design, validation, and scoring of the Atopic Dermatitis Control Tool (ADCT)

Abstract

Objectives: The Atopic Dermatitis Control Tool (ADCT) was designed to evaluate patient-perceived AD control and facilitate patient-physician discussion on long-term disease control.Methods: The study was performed in adult patients with AD. Development of the ADCT followed US Food and Drug Administration (FDA) guidelines on patient-reported outcome measures (PROMs). Qualitative research, including targeted literature review, interviews with clinical experts, and combined concept elicitation/cognitive debriefing with patients with AD, was conducted to provide a list of comprehensive concepts capturing AD control per physician and patient perspectives. Quantitative methods assessed psychometric properties of the instrument and defined the threshold for AD control.Results: The resulting pilot six-item ADCT, reflecting key concepts related to AD control, had 7-day recall and assessed symptoms and impacts on patients' everyday lives by severity and/or frequency. The ADCT showed good content validity (well understood by adult patients with AD), and quick completion time (<2 min). Psychometric analysis indicated no floor/ceiling effects for response distributions, particularly strong (r ≥ 0.80) inter-item correlations for the six ADCT items, robust construct validity (r > 0.50), and item-level discriminating ability (p < .03); this supported the derivation of a total score based on responses to all items. ADCT total score showed evidence of strong internal consistency reliability (Cronbach's alpha >0.80). A score ≥7 points was identified as an optimum threshold to identify patients whose AD is "not in control."Conclusions: No single validated instrument has been available to holistically evaluate patient-perceived AD control. The newly developed ADCT displays good-to-excellent content validity, construct validity, internal consistency, reliability, and discriminating ability.

Keywords: Atopic dermatitis; long-term disease control; patient-reported outcomes; psychometric validation.