title: The prevalence and detection of chronic kidney disease (CKD)-related metabolic complications as a function of estimated glomerular filtration rate in the oldest old.
abstract: BACKGROUND
  The prevalence of CKD rises with age. The prevalence of CKD-related metabolic complications in the oldest old in relation to different GFR estimations is largely unknown. eGFR-based thresholds for the detection of these complications remain uncertain.
  
  
  METHODS
  A cross-sectional analysis embedded within the BELFRAIL study, a population-based prospective cohort study of the oldest old in Belgium, was performed. The prevalence of anemia, elevated serum parathyroid hormone (PTH), high serum phosphorus and low uncorrected serum calcium was analyzed in relation to GFR estimated by three serum creatinine-based equations and one cystatin C-based equation.
  
  
  RESULTS
  567 patients aged 80 and over were included (63% women). The prevalence of anemia, elevated PTH and high phosphorus showed an inverse relationship with eGFR. This relationship remained after logistic regression analysis adjusting for demographics and co-morbidity. No such relationship between low calcium and eGFR was found. Using an eGFR of 60 ml/min/1.73 m(2) modification of diet in renal disease equation (MDRD) as screening threshold for metabolic complications would result in a high incidence of missed complications: 29%, 28% and 40% for anemia, elevated PTH and high phosphorus, respectively.
  
  
  CONCLUSIONS
  The presence of anemia, an elevated PTH or an elevated serum phosphorus level increased with lower eGFR but even among patients with an eGFR >60 ml/min/1.73 m(2), these complications are common. Thus this eGFR cut-off appears inadequate for patients aged 80 and over. How the oldest old may be screened appropriately for these CKD-related complications requires further investigation.
authors.affiliation: Institute of Health and Society, Université Catholique de Louvain, Clos Chapelle-aux-Champs 30, bte 3005, 1200 Brussels, Belgium. gijs.vanpottelbergh@med.kuleuven.be
authors.forename: Gijs
authors.initials: G
authors.lastname: Van Pottelbergh
authors.forename: Bert
authors.initials: B
authors.lastname: Vaes
authors.forename: Michel
authors.initials: M
authors.lastname: Jadoul
authors.forename: Catherina
authors.initials: C
authors.lastname: Matheï
authors.forename: Pierre
authors.initials: P
authors.lastname: Wallemacq
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Degryse
mesh_terms: D000369:Aged, 80 and over; D000740:Anemia / Q000453:epidemiology; D001530:Belgium / Q000453:epidemiology; D002118:Calcium / Q000097:blood; D003404:Creatinine / Q000097:blood; D003430:Cross-Sectional Studies; D055316:Cystatin C / Q000097:blood; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D008659:Metabolic Diseases / Q000097:blood / Q000453:epidemiology* / Q000209:etiology* / Q000378:metabolism; D008954:Models, Biological; D010281:Parathyroid Hormone / Q000097:blood; D010758:Phosphorus / Q000097:blood; D015995:Prevalence; D011446:Prospective Studies; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000150:complications* / Q000453:epidemiology* / Q000378:metabolism
chemical_list: D055316:Cystatin C; D010281:Parathyroid Hormone; D010758:Phosphorus; D003404:Creatinine; D002118:Calcium