Association between the neutrophil-to-lymphocyte ratio and psoriasis: a cross-sectional study of the National Health and Nutrition Examination Survey 2011-2014

Objectives To investigate the association between the neutrophil-to-lymphocyte ratio (NLR) and psoriasis.Design Cross-sectional study.Setting National Health and Nutrition Examination Survey 2011-2014.Participants A subsample of 8387 individuals aged 18 years and older were screened for inclusion, of whom 238 reported a diagnosis of psoriasis.Primary and secondary outcome measures Psoriasis and the severity of psoriasis were defined according to participants' self-reports. Weighted logistic regression, subgroup and restricted cubic spline (RCS) analyses were conducted to estimate the potential relationship of the NLR with psoriasis.Results In the fully adjusted models, the fourth quartile of the NLR was significantly and positively associated with the presence of psoriasis using the first quartile as a reference (OR: 2.22, 95% CI: 1.27 to 3.87, p=0.01). Elevated NLR was associated with an increased odds of having more severe psoriasis for the highest quartile (vs the lowest quartile), with an OR of 2.43 (95% CI: 1.10 to 5.36, p=0.003). The association between the NLR and psoriasis differed across prespecified subgroups by age, sex, race, income and education. A non-linear correlation of the NLR with psoriasis was observed using univariable and multivariable RCS (all p for non-linearity <0.05).Conclusions The NLR was non-linearly and positively correlated with the presence of psoriasis, and our findings suggest a significant association between the NLR and the severity of psoriasis. The potential role and value in the clinical diagnosis and prognostic assessment of the NLR in psoriasis calls for further longitudinal studies.