Assessing Response in Atopic Dermatitis: A Systematic Review of the Psychometric Performance of Measures Used in HTAs and Clinical Trials.

The assessment of treatment response is important in determining treatment value in atopic dermatitis (AD). This study aimed to identify which outcome measures and criteria are used to determine treatment response in clinical trials and health technology assessments (HTAs). The psychometric performance of identified outcome measures and criteria was then systematically reviewed to understand which perform best in capturing patient-relevant symptoms and treatment benefits in AD. The review identified and included the Eczema Area and Severity Index (EASI), Investigator's Global Assessment (IGA), Dermatology Life Quality Index (DLQI) and Peak Pruritus Numerical Rating Scale (PP-NRS) as response measures. Lack of consistency in how response is assessed across clinical trials and HTAs makes it difficult for clinicians and payers to compare the efficacies and cost-effectivenesses of different treatments and to make optimal treatment decisions. The review found that content validity (the extent to which a measure covers those symptoms and treatment benefits which are important to patients) was not assessed for EASI and IGA. EASI and IGA are often used to assess response in clinical trials and HTAs, but they miss key elements of the patient-relevant disease impact and treatment benefit, including itch. Treatments leading to improvements in missed symptoms (e.g. itch) will be undervalued using EASI and IGA, decreasing the chances of regulatory approval and reimbursement. Moreover, response criteria used in clinical trials and HTAs are sometimes adopted in prescriber settings. Here, if response assessment does not capture patient-relevant benefit, patients' access to tailored treatment may be restricted due to the perceived non-response.