Clinical phenotyping of atopic dermatitis using combined itch and lesional severity

Background Patients with atopic dermatitis (AD) have heterogeneous clinical phenotypes, including different combinations of itch and lesional severity. Little is known about the characteristics and course of these subtypes. Objective To determine the characteristics, associations, burden, and course of patients with AD using combined itch and lesional severity. Methods A prospective practice-based study was performed using questionnaires and physical examination (n=592). AD subsets were defined using verbal rating scale for average itch combined with either eczema area and severity index, objective—scoring atopic dermatitis (SCORAD), or validated investigator's global assessment as follows: mild-moderate itch and lesions (MI-ML), mild-moderate itch and severe lesions (MI-SL), severe itch and mild-moderate lesions (SI-ML), and severe itch and lesions (SI-SL). Results At baseline, there were only weak-moderate correlations of numerical rating scales for worst itch or average itch or SCORAD itch with eczema area and severity index, objective-SCORAD, body surface area, and validated investigator's global assessment (Spearman's rho = 0.32-0.62). Most patients had MI-ML (59.4%-62.3%), followed by SI-ML (21.3%-29.1%), SI-SL (6.0%-12.9%), and MI-SL (3.8%-6.4%). Patients with SI-SL, followed by SI-ML and MI-SL, described their AD as being more severe overall and had worse impairment in sleep, mental health, and quality of life. However, those with MI-SL or SI-SL were far more likely to be classified as severe by a physician (multivariable logistic and linear regression, P < .005 for all). Baseline MI-SL, SI-ML, and SI-SL were associated with similar longitudinal courses over time and more AD flares and itch triggers than MI-ML. Conclusion Combined itch and lesional severity seem to describe unique AD phenotypes. Further studies are needed to confirm these findings and understand the optimal treatments for these groups.