Body Roundness Index, MASLD risk and long-term follow-up outcomes among the general population

This study aimed to examine the associations of the body roundness index (BRI) with metabolic dysfunction-associated steatotic liver disease (MASLD), and long-term mortality outcomes, given that the body mass index (BMI) does not adequately reflect visceral adiposity.

Three large-scale, population-based cohorts in China (CKB, n=24,910), the United States (NHANES, n=19,889), and Europe (UKB, n=383,504) were included in this study. The primary outcomes were MASLD prevalence and all-cause mortality. Logistic regression, restricted cubic spline (RCS), and Weibull regression models were used to quantify associations of BRI with MASLD and subsequent mortality over a 10-year follow-up, with BMI as the comparator.

There was an S-shaped association between BRI and MASLD prevalence (all P<0.001). An increased risk of MASLD was observed with higher BRI (for BRI Q5, adjusted odds ratio [OR] >5.68, P<0.001), even among individuals with normal BMI and moderate waist circumference. Low BRI with high BMI did not increase the risk of MASLD, whereas the combination of high BRI and high BMI substantially elevated the risk. There was a U-shaped association between BRI and all-cause mortality in MASLD. Weibull regression analysis further indicated that both excessively low and high BRI shortened survival time, with time ratios (TR) indicating reductions ranging from 14% to 58%.

Higher body roundness index (BRI) was associated with increased MASLD risk, even in normal-weight individuals with moderate waist circumference; low BRI and high BMI did not increase MASLD risk, whereas high BRI and high BMI markedly increased it. Among individuals with MASLD, both excessively low and high BRI values were associated with increased all-cause mortality.