Clinical detection of ichthyosis vulgaris in an atopic dermatitis clinic: Implications for allergic respiratory disease and prognosis

Background: Recent genetic studies have demonstrated that filaggrin mutations, shown to underlie ichthyosis vulgaris (IV), may also predispose patients with atopic dermatitis to allergic respiratory disease. Objective: Our objective was to determine whether the clinical presence of IV influences the severity and age at onset of atopic dermatitis or the probability of having allergic respiratory disease. Methods: We reviewed data collected from the initial visits of 1187 patients with atopic dermatitis. Results: Asthma symptoms were more common in atopic dermatitis patients with IV than in those without (39.9% vs 32.9%, odds ratio [OR] = 1.35, P = .050) and were most associated with severe IV (OR = 2.52, P = .002). This relationship remained after controlling for the baseline severity of atopic dermatitis. Clinical IV was also associated with symptoms of allergic rhinoconjunctivitis, earlier onset of atopic dermatitis, severity of atopic dermatitis, hyperlinear palms, and keratosis pilaris. Limitations: Our limitations include subjective grading, few data points in some groups, and an inability to demonstrate causality. Conclusion: These results suggest that clinical evidence of IV, irrespective of filaggrin genotype, serves as a potential marker for those patients with atopic dermatitis who develop allergic respiratory disease and a more severe skin phenotype.