U-Shaped Association Between Body Roundness Index and All-Cause Mortality in Hypertensive Adults: NHANES 1999–2018 Cohort Study

Background Previous studies have shown that obesity is associated with an increased risk of various cardiovascular diseases. The Body Roundness Index (BRI) is a novel indicator for assessing body fat and visceral fat. However, the relationship between BRI and all-cause and cardiovascular mortality in individuals with hypertension remains unclear. This study aims to investigate the association between BRI and all-cause and cardiovascular mortality among US adults with hypertension. Methods This study utilized data from the National Health and Nutrition Examination Survey (NHANES) (1999–2018). The study population consisted of 20,532 hypertensive adults. Cox proportional hazards models were used to assess the association between BRI and all-cause and cardiovascular mortality. A generalized additive model were employed to evaluate potential nonlinear relationships between BRI and mortality. Results Among the 20,532 hypertensive adults (mean age: 59.5 ± 15.9 years), a total of 5,044 (25.4%) participants died during follow-up. BRI exhibited a U-shaped association with all-cause mortality, with an inflection point at 5.09. Below the inflection point, each unit increase in BRI was associated with a decreased risk of all-cause mortality (HR = 0.82, 95% CI: 0.79–0.86, P  < 0.0001); above the inflection point, each unit increase in BRI was associated with an increased risk (HR = 1.05, 95% CI: 1.04–1.07, P  < 0.0001). A similar U-shaped relationship was observed for cardiovascular mortality, with an inflection point at 4.97 (HR = 0.87 [0.80, 0.94], P  = 0.0006 below the inflection point; HR = 1.23 [1.12, 1.36], P  < 0.0001 above the inflection point). After adjusting for age, sex, race, and education level, both the lowest and highest BRI tertiles were associated with higher all-cause mortality. Conclusion Among US adults with hypertension, BRI demonstrates a U-shaped relationship with all-cause and cardiovascular mortality. Further research is needed to validate these findings.