The joint effect of triglyceride-glucose related indices and depression on cardio-renal-metabolic multimorbidity among middle-aged and older Chinese adults

BACKGROUND: The triglyceride-glucose (TyG) related indices, indicators for insulin resistance, and depression are both established predictors of cardiovascular diseases. However, the single and combined effect of TyG related indices and depression on cardio-renal-metabolic multimorbidity (CRMM) risk remain uncertain. METHODS: This study included 7848 respondents aged 45 years and older, derived from the China Health and Retirement Longitudinal Study (CHARLS) 2011, 2020. Cox regression was used to determine independent and joint effect of TyG indices and depression on CRMM incidence. Restricted cubic spline (RCS) was further performed to identify associations of TyG indices with CRMM. RESULTS: Results demonstrated that both TyG indices (including TyG-WC, TyG-WHtR, and TyG-BMI) and depression were independently linked to increased risk of CRMM. The RCS model further confirmed the significant dose-response relationships. Participants experiencing both elevated TyG indices and depression exhibited the highest CRMM risk, in contrast to those with neither condition (HR = 1.630, 95%CI: 1.467-1.811; HR = 1.631, 95%CI: 1.465-1.817; HR = 1.582, 95%CI: 1.419-1.764; HR = 1.532, 95%CI: 1.372-1.711, respectively). LIMITATIONS: Firstly, disease diagnoses in the CHARLS were self-reported, which might cause recall bias. Then, data was specific to the population over 45 years old, so the results may not apply broadly to all populations. CONCLUSIONS: This study revealed both the single and joint effect of TyG, TyG-WC, TyG-WHtR, as well as TyG-BMI and depression on CRMM risk. Combined evaluations of the TyG index with depression screening is crucial for identifying related risk factors and enhancing prevention strategies against CRMM.