Background
The relationship of systemic immune-inflammation index (SII) with mortality in hyperlipidemic patients remains unknown. In the present work, we evaluated SII for its ability to predict mortality incidence and examined its relationship with mortality of hyperlipidemic individuals.
Methods
Altogether 27,903 hyperlipidemic cases were collected during 1999-2018 following the National Health and Nutrition Examination Survey (NHANES). SII was determined with complete blood count parameters. Our main results included all-cause and cardiovascular disease (CVD) mortality. We conducted Kaplan-Meier survival, restricted cubic spline (RCS), and Cox proportional hazards model analyses to assess the connection of SII to mortality among hyperlipidemic patients. To ensure that these results were reliable, we also conducted sensitivity and subgroup analyses.
Results
For hyperlipidemic cases, their all-cause and CVD mortality rates were 12.651% and 3.916% separately. According to the Kaplan-Meier analysis, survival rates were low for individuals with high SII values. Multivariate Cox regression analysis indicated that for every one-unit elevation of lnSII, the all-cause mortality rate elevated by 19.7% (HR = 1.197, 95% CI: 1.117, 1.283), and the CVD mortality rate elevated by 30.1% (HR = 1.301, 95% CI: 1.131, 1.497). RCS suggested the U-shaped relationship of lnSII values with all-cause and CVD mortality (p < 0.0001) of hyperlipidemic individuals. According to our threshold analysis results, thresholds for lnSII were 6.08 and 5.96. Subgroup and sensitivity analyses yielded reliable results.
Conclusions
For representative hyperlipidemic patients, SII shows the non-linear, U-shaped relationship with all-cause and CVD mortality.