Cumulative visceral fat burden and progression to advanced cardiovascular kidney metabolic syndrome in Chinese middle-aged and older adults.

Visceral adiposity is increasingly recognized as a key contributor to cardiovascular-kidney-metabolic (CKM) syndrome, yet longitudinal evidence regarding both baseline visceral fat burden and cumulative metabolic exposure remains limited. The metabolic score for visceral fat (METS-VF) is a validated surrogate marker reflecting visceral adiposity and metabolic dysfunction. We investigated the associations of baseline METS-VF and cumulative METS-VF (cumMETS-VF) with progression to advanced CKM syndrome in a nationally representative cohort. We analyzed 3,322 middle-aged and older adults from the China Health and Retirement Longitudinal Study (CHARLS) who underwent repeated metabolic assessments in 2012 and 2015. Exposures included baseline METS-VF and cumMETS-VF derived from repeated measurements across the two waves. The outcome was incident advanced CKM syndrome (Stages 3-4). Multivariable logistic regression, restricted cubic spline analyses, threshold-effect analyses, receiver-operating-characteristic (ROC) analyses, subgroup analyses, and sensitivity analyses were performed. Threshold stability was further evaluated using Bootstrap resampling. During approximately four years of follow-up, 20.2% of participants progressed to advanced CKM syndrome. Higher baseline METS-VF and cumMETS-VF were independently associated with increased risk of advanced CKM syndrome after multivariable adjustment, with ORs of 1.13 (95% CI 1.06-1.22) and 1.06 (95% CI 1.04-1.09) per one-unit increment, respectively. Significant nonlinear associations were observed for both exposures (all P_non-linear < 0.001). Risk increased more markedly beyond identified thresholds of 6.71 for baseline METS-VF and 20.11 for cumMETS-VF. These threshold estimates were generally consistent across restricted cubic spline analyses, likelihood-based threshold models, ROC-derived optimal cutoffs, and Bootstrap resampling analyses. Compared with conventional adiposity indices, METS-VF and cumMETS-VF showed comparable or slightly better discrimination for advanced CKM syndrome progression (AUC approximately 0.60). Findings remained generally consistent across subgroup and sensitivity analyses. In this nationally representative cohort, both baseline and cumulative visceral adiposity burden assessed by METS-VF were independently associated with progression to advanced CKM syndrome. The observed nonlinear and threshold relationships suggest that sustained elevations in visceral adiposity burden may contribute to CKM syndrome progression. In comparative analyses, METS-VF demonstrated slightly better discriminatory performance than traditional adiposity indices. Together, these results suggest that METS-VF and cumulative METS-VF may contribute to improved risk stratification for identifying individuals at elevated risk.