Systemic inflammatory indicators and their clinical correlations in prurigo nodularis: A multicenter cross-sectional study in China

Systemic inflammatory indicators and their clinical correlations in prurigo nodularis: A multicenter cross-sectional study in ChinaTo the Editor: Prurigo nodularis (PN) is a chronic inflammatory skin disease characterized by intense pruritus and hyperkeratotic nodules. 1 Increasing evidence supports PN as a systemic inflammatory disorder rather than a purely cutaneous condition, with associations with atopic diseases, systemic diseases, and neuropsychological comorbidities. 2 However, simple and accessible biomarkers reflecting systemic inflammation in PN remain poorly defined.This multicenter cross-sectional study enrolled 390 patients with PN and 378 patients with AD from the China Type II Inflammatory Skin Disease Project (NCT05316805), along with 400 age-and sex-matched healthy controls from the 2015 China Health and Retirement Longitudinal Study.PN was diagnosed according to criteria of the International Forum for the Study of ltch, 3 with atopic PN defined by the presence of prior or concurrent atopic comorbidities.AD was diagnosed using the Hannifin-Rajka criteria.Clinical severity and patient-reported outcomes were assessed using Investigator Global Assessment, Peak Pruritus Numerical Rating Scale, Dermatology Life Quality Index, and Hospital Anxiety and Depression Scale.The following 6 complete blood count-derived systemic inflammatory indicators were calculated: neutrophil-to-lymphocyte ratio (NLR), monocyte-tolymphocyte ratio (MLR), eosinophil-to-lymphocyte ratio (ELR), basophil-to-lymphocyte ratio (BLR),