Implementation of KDIGO CKD Screening and Its Prognostic Implications in Community-Dwelling Adults Aged 75 Years or Older: A Population-Based Cohort Study

Background: Chronic kidney disease (CKD) is highly prevalent in older adults, yet distinguishing pathological CKD from age-related decline in kidney function remains challenging. KDIGO guidelines recommend combined assessment of estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (uACR), but implementation in primary care is uncertain. We evaluated CKD screening patterns, KDIGO risk categories, and the prognostic value of eGFR and albuminuria for all-cause mortality in adults aged ≥75 years. Methods: We conducted a retrospective population-based cohort study of 587,603 community-dwelling adults aged ≥75 years using Primary Care electronic records. Complete CKD screening was defined as at least two eGFR and two uACR measurements ≥ 3 months apart during 2015–2019. CKD prevalence, KDIGO risk categories, and 40-month all-cause mortality were assessed. Multivariable Cox regression models evaluated the independent and joint associations of eGFR and albuminuria with mortality. Results: Only 19.0% of participants underwent complete KDIGO-recommended screening, mainly because of limited albuminuria testing. Among screened individuals, CKD prevalence was 25.7%, with over half classified as high or very high KDIGO risk. Mortality increased progressively with declining eGFR, increasing albuminuria, and worsening KDIGO risk. Macroalbuminuria (HR 1.87, 95% CI 1.75–2.00) and eGFR < 30 mL/min/1.73 m2 (HR 1.91, 95% CI 1.79–2.04) were independently associated with mortality. Conclusions: Complete KDIGO-recommended screening was performed in only one in five adults aged ≥75 years, identifying a major implementation gap in primary care. Albuminuria provided prognostic information beyond eGFR, improving identification of older adults at highest risk of death. These findings support systematic combined eGFR–uACR assessment to improve risk stratification, guide kidney-protective management, and inform healthcare planning for ageing populations.