Association between inflammatory burden index and all-cause mortality in the general population aged over 45 years: Data from NHANES 2005–2017

The objective of this study was to investigate the association between inflammatory burden index (IBI) and all-cause mortality in the general population aged over 45 years.The study included 8827 participants from the National Health and Examination Nutrition Survey (NHANES) who were aged over 45 years. The IBI was calculated using three markers: C-reaction protein × neutrophil/lymphocyte, and all the participants were classified into four groups (Quartile 1: IBI ≤0.178, N = 2206; Quartile 2: 0.178 1.099, 2207). Cox proportional hazards regression models were used to estimate hazard ratios (HR) and 95 % confidence interval (CI) for the association between IBI and all-cause mortality. During a median follow-up of 129 month, 2431 deaths occurred. The all-cause mortality rate in Quartile 1, Quartile 2, Quartile 3 and Quartile 4 was 14.76 %, 17.67 %, 23.18 % and 29.69 %, respectively (p < 0.001). After adjustment for demographic, and potential clinical factors, higher IBI was significantly associated with an increased risk of all-cause mortality (Quartile 3 vs. Quartile 1: HR = 1.26, 95 % CI: 1.08 to 1.46, p = 0.003; Quartile 4 vs. Quartile 1: HR = 1.59, 95 % CI: 1.40 to 1.80, p < 0.001). Furthermore, the results of the restricted cubic spline analysis suggested that the association between IBI and all-cause mortality was nonlinear and positive, without specific threshold value.This study supports that higher IBI is associated with an increased risk of all-cause mortality in the general population aged over 45 years.