Measuring Long-term Disease Control in Atopic Dermatitis: a Validation Study of Well Controlled Weeks

Publication date: Available online 26 April 2017
Source:Journal of Allergy and Clinical Immunology
Author(s): Sinéad M. Langan, Beth Stuart, Lucy Bradshaw, Jochen Schmitt, Hywel C. Williams, Kim S. Thomas
BackgroundBecause atopic dermatitis (AD) is a relapsing, remitting disease, assessing long-term control is important. Well controlled weeks (WCWs) have been used to assess asthma long-term control, but never validated for AD.ObjectivesTo assess feasibility, validity and interpretability of WCWs in AD patients.MethodsThree studies of patients with moderate-to-severe AD including 4-6 months of daily/weekly symptom and treatment use data were evaluated (Study A: n=336; Study B: n=60; Study C: n=224). WCWs were defined by worsening symptoms and increased medication use. Feasibility, construct validity and interpretability of WCWs were determined by assessing missing data, association with validated AD outcomes, and floor/ceiling effects. Analysis used linear and logistic regression.ResultsWCWs were feasible to collect - 95.2% (study A) and 94.7% (study B) contributed data for at least half of the weekly data-points, and 93.2% and 88.7% contributed to all data-points up to 4 months. WCWs were significantly associated with validated AD severity instruments including patient-reported (POEM) and objective signs (EASI, TIS and SASSAD). The odds of experiencing a WCW if AD severity was clear/mild was 5.8 (95% confidence interval (CI) 3.5 to 9.7), 1.9 (95%CI 0.8 to 4.4) and 8.1 (95%CI 4.5 to 14.6) in Studies A, B and C, respectively. WCWs were associated with ceiling effects- 31.6% (study A) and 37.5% (study B) of participants had no WCWs for >90% of the time.ConclusionsWCWs are valid and feasible for measuring long-term control in AD trials. However, ceiling effects and burden of data collection may limit use.

Teaser

WCWs were feasible to collect and demonstrated construct validity (closely related to other measurements of AD severity); however, ceiling effects may be problematic in patients with moderate to severe disease.


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