Reclassification of Chronic Kidney Disease in the Elderly: Integrating Age-Adjusted GFR and Frailty Assessment in a Regional Italian Population (Abruzzo)

Background: Chronic kidney disease (CKD) is increasingly prevalent among the elderly, yet current diagnostic criteria often fail to distinguish between true CKD and age-related physiological decline in glomerular filtration rate (GFR). This overestimation can lead to overdiagnosis, overtreatment, and psychological distress. Frailty, a common condition in older adults, further complicates the clinical picture. This study aimed to reclassify CKD in the elderly by integrating age-adjusted GFR estimation and frailty assessment in a regional Italian population. Methods: Retrospective, population-based study involving 325,622 individuals aged ≥65 years residing in the Abruzzo region. Data included serum creatinine, eGFR (CKD-EPI), urine tests, renal imaging, and frailty measures using the Clinical Frailty Scale (CFS) and Fried Frailty Criteria (FFC). The Keller formula (GFR = 130 − age) was applied to distinguish between physiological renal aging and pathological CKD. Patients were categorized into four groups: Robust CKD, Senescent Nephropathy, Robust Aged Kidney, and Frailty Aged Kidney. Results: Of the 58,611 elderly patients classified with CKD stages G3–G5 based on CKD-EPI, only 27.9% (65–74 years), 56.0% (75–84 years), and 54.0% (≥85 years) had eGFR values below age-adjusted expectations. More than 40% of patients met criteria for renal senescence rather than true CKD. Over 50% of CKD patients fell into frail phenotypes (Senescent Nephropathy or Frailty Aged Kidney), emphasizing the need for a multidimensional clinical approach. Conclusions: Reclassifying CKD using age-adjusted GFR and frailty assessment improves diagnostic accuracy in the elderly, preventing misdiagnosis and guiding personalized care. This approach supports a shift from static staging to a more nuanced, patient-centered nephrological model that integrates renal physiology and geriatric assessment.