Combined effects of cumulative triglyceride-glucose and blood pressure on stroke in middle-aged and older Chinese adults: a longitudinal analysis

Background: The triglyceride-glucose (TyG) index has increasingly been recognised an indicator for stroke risk. We aimed to explore the relationship between TyG and blood pressure (BP) and the combined effects of cumulative TyG (CumTyG) and cumulative BP (CumBP) on stroke risk in a cohort of Chinese middle-aged and older adults. Methods: We enrolled 5138 participants from the 2011-2018 waves of the China Health and Retirement Longitudinal Study. Cumulative TyG and BP exposures were recorded between 2011 and 2015, and stroke incidence was then followed up until 2018. We conducted a cross-lagged panel analysis to address the temporal and directional relationships between TyG and BP, used logistic regression analysis to determine the effects of CumTyG and CumBP on stroke onset, and employed three machine learning methods to identify the key risk factors and develop a predictive model for stroke. Results: High TyG levels in 2011 predicted higher systolic BP (SBP) in 2015 (β1 = 0.026; 95% confidence interval (CI) = 0.001-0.051), and high systolic BP (SBP) in 2011 predicted higher TyG in 2015 (β2 = 0.028; 95% CI = 0.003-0.053). We observed analogous results in the cross-lag between TyG and diastolic BP (DBP). Compared with individuals in lower CumTyG (<8.62) and cumulative SBP (CumSBP<140 mm Hg), those with higher CumTyG and CumSBP had an increased stroke risk (adjusted odds ratio (aOR) = 1.709; 95% CI = 1.212-2.410). Logistic regression analysis showed similar effects of CumTyG and cumulative DBP (CumDBP) on stroke onset. Seven refined consensus factors were selected to develop the predictive model, by which the area under the receiver operating characteristic curve for prediction of stroke was 0.681 (95% CI = 0.647-0.715) in training and 0.631 (95% CI = 0.573-0.689) in validation sets. Conclusions: Our findings are indicative of a bidirectional relationship between TyG and BP. Sustained exposure to high levels of TyG index and BP may increase stroke risk.