The association of Neutrophil-to-Lymphocyte ratio with metabolic syndrome in U.S. Adults: Findings from the 1999-2018 National Health and Nutrition Examination survey.

Background: Identifying and treating metabolic syndrome (MetS) early is of great importance, as MetS portends numerous negative health outcomes. Identifying an inexpensive, readily available inflammatory biomarker that accurately predicts MetS could be of use to clinicians.

Methods: The aim of this study was to evaluate the relationship between the neutrophil-to-lymphocyte ratio (NLR) and MetS in U.S. adults. We used data from adult participants of the 1999-2018 National Health and Nutrition Examination Surveys to conduct a cross-sectional study. MetS was determined using National Cholesterol Education Program Adult Treatment Panel III (2005 revision) criteria; NLR was calculated by dividing the absolute neutrophil count by absolute lymphocyte count. Data were weighted and analyzed using survey procedures in SAS v9.4.

Results: Data from 101,316 participants were reviewed, of whom 19,613 were eligible for weighted analysis. MetS was observed in 40.3 % of participants (n = 7,896), who met 3  = 3,902; 49.4 %), 4 (n = 2,817; 35.7 %), and 5 (n = 1,177; 14.9 %) criteria of MetS, respectively. Across the survey years, NLR was higher in those with MetS compared to those without (mean 2.24 [95 % CI 2.21, 2.28] vs 2.05 [95 % CI 2.02, 2.08];  < 0.001). There was a consistent trend of increasing NLR according to MetS severity ( < 0.001). An NLR cutoff of 1.67 had 74.3 % sensitivity and 62.3 % specificity for MetS with Area-under-the-curve of 0.736 [95 % CI 0.73, 0.74].

Conclusions: Among U.S. adults, NLR was associated with MetS and MetS severity, independent of age and race/ethnicity.