Significance of eGFR and proteinuria for cardiovascular disease in individuals beyond 85 years of age.

Background: There are limited data on how advancing age influences prediction of cardiovascular disease (CVD) risk based on the estimated glomerular filtration rate (eGFR) and proteinuria, especially in older adults, including those aged ≥85 years old. This study aimed to clarify the association of eGFR and proteinuria with CVD outcomes and the impact of age on this association.

Methods: The distribution of eGFR and urine protein in Japan was assessed retrospectively using real-world administrative claims and health checkup data collected between April 2014 and November 2022. We investigated the associations of these two parameters with the incidence of CVD, with an emphasis on the impact of aging.

Results: We assessed 1 829 020 individuals for distribution of eGFR and proteinuria; after excluding those with known CVD, their association with CVD risk was examined in 1 040 101 individuals aged ≥40 years. The prevalence of impaired kidney function (eGFR <60 mL/min/1.73 m2) increased with age, being 0.7%, 9.2%, 21.9%, 40.2% and 60.2% at the ages of 18-39, 40-64, 65-74, 75-84 and ≥85 years, respectively (P for trend <.001); similarly, the proportion with positive proteinuria increased with age, being 2.7%, 4.3%, 5.6%, 9.2% and 15.8%, respectively (P for trend <.001). Both eGFR and urine protein were identified to be independent risk factors for CVD. Hazard ratios for CVD increased significantly when eGFR was <45 mL/min/1.73 m2 at the ages of 40-64, 65-74 and 75-84 years and <30 mL/min/1.73 m2 at ≥85 years, while proteinuria remained significantly associated with a high CVD risk regardless of age. These findings were consistent even when analyzed separately by sex.

Conclusions: This study identified eGFR and urine dipstick proteinuria to be independent risk factors for CVD, even among individuals aged ≥85 years. However, the contribution of eGFR to the CVD risk was attenuated by aging, whereas proteinuria remained less affected by advancing age.