The association between visceral adiposity index and long-term all-cause mortality shows age-related disparities: a nationwide cohort study.

BACKGROUND

The prevalence of obesity has increased rapidly worldwide over the past few decades and remains a recognized public health concern. However, studies exploring visceral adiposity index (VAI), a sex-specific indicator reflecting visceral fat distribution and function, and long-term mortality are limited. This study aimed to investigate the association of VAI with long-term all-cause mortality among general adults in the United States.

METHODS

This cohort study used data from the National Health and Nutrition Examination Survey (NHANES) 1999-2018. Participants were linked to National Death Index mortality data through December 31, 2019. Weighted Cox proportional hazards regression model was used to calculate hazard ratios (HRs) and 95% CIs, and restricted cubic spline (RCS) was also conducted.

RESULTS

A total of 21,943 US adults (weighted mean age, 46.9 years; 10,921 males [weighted, 49.1%]) were included. During 211,473 person-years of follow-up (median follow‑up: 9.3 years), 3326 total deaths occurred. After multivariable adjustments, compared with the 3rd quintile (Q3) of VAI, participants in the 2nd (Q2) and 5th (Q5) quintiles were at a significantly higher risk of all-cause mortality (HR 1.16 [95% CI, 1.00-1.34] and HR 1.15 [95% CI, 1.01-1.31], respectively). RCS revealed a U-shaped relationship of log-transformed VAI to all-cause mortality (P for nonlinearity < 0.001), with an inflection point of 0.824. Subgroup analysis indicated that there was a significant interaction of VAI with age on all-cause mortality (P for interaction = 0.005). Higher VAI levels were associated with higher all-cause mortality in younger adults (Q5 vs. Q3, HR 1.56 [95% CI, 1.12-2.18], P = 0.009) rather than older adults (Q5 vs. Q3, HR 1.05 [95% CI, 0.91-1.22], P = 0.497).

CONCLUSIONS

In the nationally representative cohort of US adults, VAI was nonlinearly associated with long-term all-cause mortality and the association showed age-related disparities. A higher VAI was related to a higher mortality risk in younger adults. These findings underscore the importance of appropriate VAI for long-term health outcomes, especially for young adults.