Hemodynamic gain index and risk of chronic kidney disease: A prospective cohort study of middle-aged and older men.

The hemodynamic gain index (HGI), a novel non-invasive hemodynamic marker, represents a promising advancement in cardiovascular risk assessment. Cardiovascular disease and chronic kidney disease (CKD) are closely intertwined and share bidirectional relationships. We aimed to assess the association of HGI with CKD risk in a prospective study. Hemodynamic gain index was calculated using heart rate and systolic blood pressure (SBP) responses measured in 1765 men aged 42-61 years with normal kidney function during exercise testing using the formula: [(Heart rate max x SBP max )-(Heart rate rest x SBP rest )]/(Heart rate rest x SBP rest ). Multivariable adjusted hazard ratios (HRs) (95% confidence intervals, CIs) were estimated for CKD. Over a median follow-up duration of 25.9 years, 175 CKD cases occurred. In analysis adjusted for established risk factors, a unit (bpm/mmHg) higher HGI was associated with a decreased risk of CKD (HR 0.78, 95% CI 0.65-0.95). Comparing extreme tertiles of HGI, the corresponding adjusted HR (95% CI) for CKD was 0.53 (0.33-0.85). Addition of HGI to a CKD risk prediction model containing established risk factors improved risk discrimination and reclassification (p-value for difference in -2 log likelihood = .011; net-reclassification-improvement = 59.37%, p = .018; integrated-discrimination-improvement = 0.0064, p = .008). Higher HGI is associated with a lower CKD risk and improves the prediction and classification of CKD beyond common established risk factors.