Inflammatory burden index is correlated with increased depression: a population-based study.

Background: Depression is intricately correlated with systemic inflammatory responses. The Inflammatory Burden Index (IBI) has recently been introduced as a comprehensive metric for evaluating systemic inflammation. This study aims to explore the correlation between IBI and depression in the general population.

Methods: This cross-sectional study was designed to analyze the data from National Health and Nutrition Examination Survey (NHANES) during the period from 1999 to 2018. IBI was formulated as C-reactive protein×neutrophils/lymphocytes. The correlation between the prevalence of depression and IBI was explored through multivariate logistic regression analyses, as well as subgroup, interaction, restricted cubic spline (RCS) and sensitivity analyses.

Results: A total of 14,557 subjects were included in this study, of whom, 1231 (8.5%) had depression. According to multivariate logistic regression and RCS analyses, a significantly linearly positive correlation was observed between IBI and depression [odds ratio (OR) = 1.03, 95% confidence intervals (CI): 1.01, 1.05, P = 0.007]. Subjects in the third tertile of IBI exhibited a significantly higher prevalence of depression, with 40.0% affected, compared to those in the first tertile (P < 0.001). This correlation was consistently observed across all subgroups through stratified analysis (all interaction P > 0.05). After sensitivity analyses excluding participants with upper and lower 2.5% of IBI, the correlation between IBI and depression remained stable (OR = 1.08; 95%CI, 1.01, 1.15, P < 0.001).

Conclusion: These findings in this study indicate a positive correlation between IBI and depression in American adults. Further large-scale prospective studies are still needed to analyze the role of IBI in depression.