The Correlations between Complete Blood Cell Count-Derived Inflammatory Indices and Obesity and Mortality Rates: The National Health and Nutrition Examination Survey, 1999-2018

Background: Inflammation plays a crucial role in the pathogenesis of obesity, and complete blood cell count (CBC)-derived inflammatory indices have increasingly been studied as a novel biomarker class. The relevance of these biomarkers to obesity and prognostic outcomes, however, remains uncertain. Therefore, the present study was designed to assess the associations among CBC-derived inflammatory biomarkers, obesity, cardiovascular disease (CVD) mortality, and all-cause mortality in the general public. Methods: The National Health and Nutrition Examination Survey (NHANES) dataset was leveraged to conduct this analysis with data collected from 1999-2018. The relationships between CBC-derived inflammatory biomarkers and obesity were analyzed by multivariate logistic regression. Furthermore, the correlations between these CBC-derived inflammatory biomarkers and both CVD and all-cause mortality in obese individuals were assessed employing a weighted regression approach. However, the linearity of these relationships was evaluated utilizing a restricted cubic spline (RCS) regression approach. Moreover, a random survival forest (RSF) model was used to estimate the relative significance of certain inflammatory biomarkers as risk factors associated with all-cause mortality in obese individuals. Results: Multivariate analyses showed that the highest quartile of CBC-derived inflammatory indices was independently associated with a higher prevalence of obesity. RCS regression analyses revealed non-linear associations of CBC-derived inflammatory indices with CVD and all-cause mortality in obese individuals. Furthermore, RSF models identified the [neutrophils + monocytes]/lymphocytes ratio (NMLR) as the most important predictor of all-cause mortality. Conclusion: These analyses revealed that high CBC-derived inflammatory biomarker levels were linked to an increase in the prevalence of both general and abdominal obesity. Among obese individuals, the relationship between elevated CBC-derived inflammatory biomarker levels and both CVD and all-cause mortality conformed to a non-linear "U" shape. Furthermore, NMLR emerged as the most relevant predictor for all-cause mortality.