The ZJU index as a predictor of all-cause mortality in metabolic syndrome patients: A prospective cohort study from NHANES 2005–2018

The ZJU index, an innovative metabolic marker, combines triglycerides, fasting plasma glucose, body mass index, and the ratio of alanine aminotransferase to aspartate aminotransferase. This study examines how ZJU index variations correlate with all-cause mortality risk in US adults with metabolic syndrome (MetS). Data were obtained from 6020 individuals with MetS, extracted from the 2005-2018 National Health and Nutrition Examination Survey dataset, and linked to the National Death Index. Using multivariable Cox regression and restricted cubic splines, the impact of the ZJU index on all-cause mortality was evaluated. To identify the inflection points, piecewise Cox proportional hazards modeling was applied. Additionally, subgroup analyses and interaction assessments aimed to evaluate the consistency and reliability of the ZJU index. After multivariable adjustment, a U-shaped nonlinear relationship was identified, associating the ZJU value with all-cause deaths in MetS patients. Specifically, below a ZJU index threshold of 46.25, lower values were inversely correlated with mortality (hazard ratio 0.95, 95% CI 0.91-0.99). Above this threshold, there was a positive connection (hazard ratio 1.04, 95% CI 1.00-1.08) with death. Maintaining the ZJU index within an optimal range may reduce mortality risk in MetS patients.