Association Between Relative Fat Mass and the Serum Creatinine/Cystatin C Ratio and Cardiometabolic Multimorbidity: Evidence From Two Large Population-Based Surveys.

Higher SCR/CysC levels were significantly negatively associated with the risk of cardiometabolic multimorbidity in both Chinese and American populations.

• Study included 9292 Chinese participants from the CHARLS database and 3822 American individuals from the NHANES database.
• In CHARLS, the highest quartile (Q4) of SCR/CysC compared to the lowest quartile (Q1) was associated with decreased CMM risk: OR = 0.89, 95% CI: 0.87–0.91, p < 0.001.
• In NHANES, the highest quartile (Q4) of SCR/CysC compared to Q1 was associated with decreased CMM risk: OR = 0.90, 95% CI: 0.86–0.94, p < 0.001.
• Multivariate logistic regression, restricted cubic spline plots, and subgroup analyses were used to explore these associations.
• Results were consistent after adjusting for multiple confounding factors.

Higher relative fat mass (RFM) levels were significantly positively associated with the risk of cardiometabolic multimorbidity in both cohorts.

• In CHARLS, the highest quartile (Q4) of RFM compared to Q1 was associated with increased CMM risk: OR = 1.18, 95% CI: 1.16–1.21, p < 0.001.
• In NHANES, the highest quartile (Q4) of RFM compared to Q1 was associated with increased CMM risk: OR = 1.20, 95% CI: 1.15–1.25, p < 0.001.
• The association was replicated independently in two large population-based surveys from different countries.
• RCS plot results supported a positive relationship between RFM and CMM risk after adjustment for multiple confounding factors.

Restricted cubic spline analyses confirmed nonlinear dose-response relationships between both SCR/CysC and RFM with CMM risk.

• RCS plots demonstrated that a decrease in SCR/CysC was associated with a higher risk of CMM.
• RCS plots demonstrated that an increase in RFM was associated with a higher risk of CMM.
• These relationships were observed after adjusting for multiple confounding factors.
• Findings were consistent across both the CHARLS and NHANES databases.

SCR/CysC and RFM reflect muscle and fat content respectively and are proposed as potential biomarkers for cardiometabolic multimorbidity screening.

• SCR/CysC is described as an important indicator reflecting muscle content, while RFM reflects fat content.
• Both indicators are stated to be closely related to metabolic diseases and cardiovascular diseases.
• The authors propose these measures may serve as tools for early identification and intervention of CMM.
• The study provides evidence from two large population-based surveys to support this proposed clinical utility.

The study populations included large samples from both China and the United States to provide cross-national evidence.

• 9292 Chinese participants were drawn from the CHARLS (China Health and Retirement Longitudinal Study) database.
• 3822 American individuals were drawn from the NHANES (National Health and Nutrition Examination Survey) database.
• Total combined sample size across both databases was 13,114 participants.
• Subgroup analyses were also performed in addition to multivariate logistic regression and RCS analyses.