Association of lipid accumulation product with the prevalence and incidence of sarcopenia: a nationwide study in Chinese.

Background: Lipid accumulation product (LAP) has recently gained attention as a novel indicator of metabolic dysfunction. However, the association between LAP and sarcopenia, a metabolic condition characterized by loss of muscle mass, strength, and function, remains unclear. This study aimed to explore the relationship between LAP and both the prevalence and incidence of sarcopenia using data from the China Health and Retirement Longitudinal Study (CHARLS).

Methods: Sarcopenia was defined according to the criteria established by the Asian Working Group for Sarcopenia in 2019. LAP was calculated using waist circumference and triglyceride levels. A cross-sectional analysis was performed with 7,004 participants from the baseline survey, utilizing logistic regression models to evaluate the association between LAP and sarcopenia prevalence. Additionally, a longitudinal cohort analysis involved 4,484 individuals who were free of sarcopenia at baseline and followed from 2011 to 2015. Cox proportional hazards models were employed to assess the longitudinal association between baseline LAP levels and incident sarcopenia. Furthermore, restricted cubic spline regression (RCS) and subgroup analyses were conducted to explore potential nonlinear relationships and differences across various subgroups. Receiver operating characteristic (ROC) curves was used to evaluate the discriminatory ability of LAP for identifying sarcopenia.

Results: Cross-sectional analyses and RCS revealed a significant inverse linear relationship between LAP and the prevalence of sarcopenia [odds ratio (OR) = 0.95, 95% confidence interval (CI): 0.94-0.96]. Participants within the highest LAP tertile demonstrated substantially lower odds of sarcopenia compared to those in the lowest tertile (OR = 0.21, 95% CI: 0.14-0.31). Longitudinal analyses similarly indicated that elevated LAP levels were associated with reduced sarcopenia incidence, with the highest LAP tertile associated with notably decreased risk (HR = 0.17, 95% CI: 0.11-0.27). The nonlinear pattern identified through RCS analysis indicated significant risk reductions up to a LAP threshold of 27.577. Furthermore, subgroup analyses consistently supported this inverse association across various demographic and clinical subgroups. Finally, diagnostic performance of LAP was assessed using the ROC curve (0.763 ([CI]: 0.744-0.783) in the longitudinal study).

Conclusions: Elevated LAP levels are inversely associated with both the prevalence and incidence of sarcopenia among middle-aged and elderly adults in China. These findings suggest LAP could serve as a useful metabolic indicator for predicting reduced sarcopenia risk, warranting additional studies to confirm and further elucidate these relationships.