Load-capacity index and cardiometabolic risk: a longitudinal meta-analysis

The load-capacity index (LCI), defined as the ratio of fat mass to fat-free mass, represents a novel composite biomarker integrating metabolic load and functional capacity. This systematic review and meta-analysis aimed to determine the longitudinal association between LCI and incident cardiometabolic disease risk.

We systematically searched PubMed, Embase, Web of Science, Cochrane Central, and Scopus from inception through January 2026 for longitudinal cohort studies reporting the association between LCI and cardiometabolic outcomes. Random-effects meta-analysis was performed using the DerSimonian-Laird method. Heterogeneity was assessed using Cochran's Q, τ², and I² statistics. Study-specific log(HR) values and standard errors are reported in the Supplementary Material to enable full reproducibility.

Eighteen longitudinal cohort studies comprising 129,777 participants and 5647 cardiometabolic events were included (mean follow-up: 11.4 years). Higher LCI was significantly associated with increased cardiometabolic risk (pooled HR = 1.174, 95% CI: 1.145-1.204; p < 0.0001). There was low between-study heterogeneity (I² = 11.6%; Cochran's Q = 19.22, df = 17, p = 0.3159; τ² = 0.000347). The association was consistent across age groups, sex, and body composition assessment methods (p-interaction > 0.05 for all). LCI provided incremental predictive value beyond established risk factors (NRI: 0.15-0.28; ΔC-statistic: 0.025-0.041).

Higher LCI is independently and consistently associated with increased cardiometabolic disease risk across diverse populations (HR = 1.174, corresponding to a 17.4% increased risk per unit increase). LCI provides clinically meaningful incremental predictive value and warrants consideration as a robust supplementary tool to guide preventive interventions.