Association Between Relative Fat Mass and Cardiometabolic Disease: Age-Stratified Analysis in Young and Middle-Aged...

Current evidence characterizing the association between relative fat mass (RFM) and cardiometabolic disease (CMD) remains limited, with critical gaps persisting in the understanding of age-dependent heterogeneity. Thus, this study aimed to assess the association between RFM and CMD risk across age groups.

This study utilized data from the China Health Evaluation And Risk Reduction Through Nationwide Teamwork (ChinaHEART), and enrolled 93,801 community-dwelling adults. CMD was defined as a composite diagnosis that included diabetes mellitus, myocardial infarction, and stroke. Meanwhile, RFM was derived from height, waist circumference, and sex. Participants were stratified into groups of young and middle-aged adults (35-59 years) and older adults (≥60 years). Multivariable logistic regression models were employed to estimate odds ratios (ORs) and 95% confidence intervals (CIs), and to test for interaction effects. Restricted cubic spline models were applied to examine dose-response relationships.

Among the 93,801 participants, 18,473 (19.69%) had CMD. In the fully adjusted models, each unit increase in RFM was associated with a 9% increase in CMD risk (OR = 1.09, 95% CI: 1.08-1.09). Compared to the lowest RFM quartile (Q1), higher risks were observed in the Q2 (1.68, 1.59-1.77), Q3 (2.56, 2.34-2.80), and Q4 (4.02, 3.68-4.39) groups (p for trend <0.001). A significant RFM-age interaction was identified (p for interaction = 0.001). Restricted cubic splines confirmed significant non-linear dose-response relationships (both p for overall association <0.001; p for non-linear <0.05), with distinct age-specific patterns. Older adults exhibited higher overall CMD risk compared to young and middle-aged adults. The lower RFM inflection point corresponds to an OR of 1 (30 vs. 34), highlighting the greater vulnerability of this age group and informing the future development of age-specific RFM thresholds.

RFM demonstrates a significant positive association with CMD risk, exhibiting age-dependent heterogeneity, and emphasizing age-tailored interventions for CMD prevention strategies.