Systemic immune-inflammation index and long-term mortality in patients with hypertension: a cohort study

Objective: The objective of this study was to examine the relationship between systemic inflammation and long-term mortality in patients with hypertension. Methods: The study employed a retrospective cohort design. The study population was derived from the National Health and Nutrition Examination Survey (NHANES), and the mortality data for this population was acquired from the National Death Index (NDI) database. Systemic inflammation was quantified by the Systemic Immune Inflammation Index (SII) and the Systemic Inflammatory Response Index (SIRI), which were then categorized into four groups (Q1–Q4, with Q4 representing the highest level of SII or SIRI). Weighted Cox regression models were constructed to investigate the association between mortality and SII and SIRI, with hazard ratios (HRs) subsequently calculated. Results: A total of 7431 participants were included in the analysis. The highest quantile (Q4) of SII was associated with a higher risk of all-cause mortality (hazard ratio 1.36, 95% CI 1.1–1.69, P < 0.001). After adjustment for important covariates, the association remained significant (hazard ratio 1.70, 95% CI 1.27–2.30, P < 0.001). The highest quantile (Q4) of SIRI was also associated with the highest risk of mortality (hazard ratio 2.11, 95% CI 1.64–2.70, P < 0.001), and this association remained significant after adjustment for important covariates (hazard ratio 1.64, 95% CI 0.61–1.22, P = 0.001). Conclusion: Both SII and SIRI scores were found to be associated with mortality rates in patients with hypertension. The findings suggest that these scores may serve as complementary biomarkers to the neutrophil-to-lymphocyte ratio (NLR) for assessing mortality risk in patients with hypertension. Further investigation is warranted to elucidate the underlying mechanisms that underpin this association.