Complex interaction of waist circumference, cardiometabolic markers, and sex on elderly mortality: a cohort study of 0.4 million UK adults.

This prospective cohort study included 408,760 older adults to investigate complex interaction between waist circumference (WC), blood glucose (BG) or blood pressure (BP), and sex in relation to elderly mortality. We used Cox regression models incorporating a tensor product interaction function to model joint impacts of WC and four cardiometabolic markers on mortality, and developed a two-dimensional exposure-response function (ERF) to quantify the population adaptability to cardiometabolic dysfunction across different WC levels. The linear and nonlinear effects of BG and BP on mortality varied by WC, with significant synergistic interactions. The two-dimensional ERF quantified variations in excess mortality risk across different WC and cardiometabolic marker combinations. Individuals with higher WC exhibited a forward shift in risk thresholds, indicating reduced adaptability to elevated BG and BP levels. Our findings highlight the need for targeted cardiometabolic health management strategies to enhance adaptability and reduce the burden of cardiometabolic diseases in aging populations.