Declining Estimated Glomerular Filtration Rate and Its Association with Mortality and Comorbidity Over 10 Years in Elderly Women

Background/aims: Renal function deteriorates with age, but a few studies have addressed this longitudinally in elderly women. Our objective was, using 5 estimated glomerular filtration rates (eGFR)-equations, to evaluate changes in renal function and association with adverse outcomes for a decade in 75-year-old women.

Methods: Plasma creatinine was measured at ages 75 (n = 1,011), 78 (n = 827), 80 (n = 689) and 85 (n = 363). Glomerular filtration rates were estimated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI); Modification of Diet in Renal Disease (MDRD); revised Lund-Malmö (LM-rev); Berlin Initiative Study 1 (BIS1) and Cockcroft-Gault/body surface area (CG/BSA) equations. Mortality and comorbidity were investigated in women with chronic kidney disease (CKD) stage 3A and 3B-5.

Results: Approximately, 95% of women had eGFR indicating CKD stage 2-3 and progression towards stage 3 was continuous. The women lost 22% of their eGFR during follow-up and loss accelerated between 80 and 85. Mean loss per decade was 16.6 ml/min/1.73 m(2). Women in CKD stage 3B-5 had an adjusted hazard ratio for death of 3.5 (95% CI 2.1-5.8) compared to stage 1-2 during follow-up and increased risk of diabetes, heart failure and hypertension. The CG/BSA, BIS1 and LM-rev equations continuously predicted lower eGFR than the MDRD and CKD-EPI equations.

Conclusion: eGFR in women aged 75-85 ranges from 30 to 89 ml/min/1.73 m(2) (stage 2-3). Decline was 16.6 ml/min/1.73 m(2) per decade; accelerated with age and appeared nonlinear. Women with CKD 3B-5 demonstrate an over 3-fold risk of death. eGFR <45 ml/min/1.73 m(2) was associated with mortality, confirming the new KDIGO classification 3A and 3B, as clinically applicable in the elderly.