Threshold effect of systemic immune inflammatory index on hypertension in American adults (NHANES 2017-2020)

Background and aims: Research reports on the relationship between systemic immune-inflammation index (SII) and hypertension are limited. We aim to evaluate the possible relationship between SII and hypertension.Methods and results: We conducted a cross-sectional analysis of adults from the National Nutrition and Health Database from 2017 to 2020. In this study, 13 742 participants were included. The exposure variable in this study was the systemic inflammatory state as defined by SII and an outcome was hypertension. There is a nonlinear association between SII and hypertension. Two piecewise logistic regression models were used to analyze the relationship between them and calculated the cut-off point of SII to be 501.2. We found that SII on the left side of the cut-off point has nothing to do with the prevalence of hypertension. However, in patients with SII at least 501.2, the prevalence of hypertension increased with the increase of SII (odds ratio, 3.13; 95% confidence interval, 2.04-4.81). The nonlinear association between LgSII and hypertension still existed stably in the subgroups of sex, age, BMI, diabetes, and cardiovascular disease (P for interaction > 0.05).Conclusion :A cross-sectional analysis reported the threshold effect of SII on and hypertension and calculated the turning point of SII to be 501.2.