Hematological Markers in Children and Adults with Atopic Dermatitis: A Retrospective Cohort Study.

ABSTRACT

INTRODUCTION: Atopic dermatitis (AD) is a common chronic skin disease with an inflammatory pathophysiology that includes the activation of the innate and adaptive immune systems. We aimed to investigate the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), eosinophil-to-lymphocyte ratio (ELR), and eosinophil-to-neutrophil ratio (ENR) in AD patients, according to age and disease severity. METHODS: This is a retrospective, population-based cohort study conducted between the years 2005 and 2020, comparing hematological markers of AD patients and sex-age-ethnicity-matched controls. AD patients were further divided by age and disease severity (mild, moderate-to-severe AD). We created a decision tree to predict moderate-severe AD. RESULTS: A total of 13,928 patients with AD were included in this study 6,828 adults and 7,100 children, with 13,548 controls. NLR, PLR, and ELR were lower in children compared to adults (p values <0.001). NLR, PLR, ELR, and ENR were increased in moderate-severe AD patients compared to mild AD patients (p values <0.001). PLR, ELR, and ENR were increased in AD patients versus controls (p values <0.001), with an additional increase in the NLR of moderate-to-severe AD patients. Patients with an ELR <0.21, a PLR >161, and ENR ≤0.016 should be considered high risk for developing severe AD, as well as patients with an ELR >0.21 and age at diagnosis <30 or age >30 years and mean platelet volume ≤9. CONCLUSION: Hematological ratios were significantly higher in moderate-to-severe AD patients, compared to mild AD patients. Hematological markers were lower in children with AD compared to adults, except for ENR, likely reflecting age-related changes in blood count parameters. These markers can assist in the management and follow-up of AD patients.