title: Estimation of the age-dependent decline of glomerular filtration rate from formulas based on creatinine and cystatin C in the general elderly population.
abstract: OBJECTIVE
  To evaluate the performance of estimation formulas for glomerular filtration rate (GFR) based on creatinine and cystatin C in elderly.
  
  
  METHODS
  This study includes 2,931 men and women comprising nine age cohorts (60-93 years) from a longitudinal population-based project in Sweden. The participants were divided into four age groups. GFR was estimated from four formulas: the Modification of Diet in Renal Disease (MDRD), CKD-EPI and Cockroft-Gault (CG) based on creatinine and one based on cystatin C (eGFR-CysC). CG was also adjusted for body surface area (BSA) to CG/BSA.
  
  
  RESULTS
  CG, CG/BSA and eGFR-CysC yielded significantly lower GFR values compared to MDRD and CKD-EPI in the oldest persons (>80 years). A low GFR (<30 ml/min/1.73 m²) was demonstrated with MDRD in 3.3% (80-89 years) and in 6.3% (>90 years). With CG/BSA it was 8.0% (80-89 years) and 27.2% (>90 years), and with eGFR-CysC it was 12.1% (80-89 years) and 27% (>90 years), respectively. The individual formulas showed different eGFR in the four age cohorts and also different slopes by increasing age. CG/BSA and eGFR-CysC both show steeper declines than MDRD and CKD-EPI.
  
  
  CONCLUSIONS
  Age-associated decline of renal function is common in elderly and increases immensely after the age of 80 years. More than 25% of the oldest demonstrate eGFR <30 ml/min/1.73 m². CG and eGFR-CysC yielded the highest prevalence of decline and MDRD the lowest.
authors.affiliation: Division of Nephrology and Transplantation, Department of Clinical Sciences, Malmö University Hospital, Malmö, Sweden. Anders.christensson @ med.lu.se
authors.forename: Anders
authors.initials: A
authors.lastname: Christensson
authors.forename: Sölve
authors.initials: S
authors.lastname: Elmståhl
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001699:Biometry / Q000379:methods*; D003404:Creatinine / Q000097:blood*; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D051436:Renal Insufficiency, Chronic / Q000453:epidemiology
chemical_list: D055316:Cystatin C; D003404:Creatinine