title: Relationship between renal function and functional decline: role of the estimating equation.
abstract: BACKGROUND
  Several formulas are available to estimate glomerular filtration rate (GFR) at the bedside. A decrease in GFR has been associated with poorer performance. We hypothesized that it is related to worsening disability as well. The aim of this study was to evaluate whether the Modification of Diet in Renal Disease formulas can predict worsening disability better than the classic Cockcroft-Gault formula or the measured creatinine clearance.
  
  
  METHODS
  We studied 666 participants in the InCHIANTI study with 6 years of follow-up data. We evaluated whether directly measured creatinine clearance and GFR estimated using the Modification of Diet in Renal Disease and Cockcroft-Gault formulas predict new disability defined as the loss of ≥ 1 ADL over the 6-year follow-up.
  
  
  RESULTS
  The mean age was 73.1 years (SD: 6.1), 57.7% were women. Fewer than 5% of participants were disabled at baseline. Eighty-one (12.2%) participants experienced a decline in activities of daily life score at follow-up. Declining GFR was associated with increasing risk of worsening disability (Mantel-Haenszel P < .001), with an increased steepness in the curve at GFR below 60 mL/min. The relative risks for worsening disability in people with GFR less than 60 mL/min/m were 3.19 (95% CI: 2.12-4.79) and 4.40 (95% CI: 2.80-6.94) using the Modification of Diet in Renal Disease and the Cockcroft-Gault equations, respectively. The corresponding figures obtained with measured creatinine clearance was 3.95 (95% CI: 2.60-6.01). After adjustment for potential confounders, however, these estimates were substantially reduced.
  
  
  CONCLUSIONS
  Estimation of renal function with the Cockcroft-Gault or Modification of Diet in Renal Disease formulas can help to identify elderly at risk of worsening disability. The mechanism by which reduced kidney function predicts disability should be further investigated.
authors: Area di Geriatria, Università Campus Biomedico, Roma, Italy. c.pedone@unicampus.it
authors: Claudio
authors: C
authors: Pedone
authors: Andrea
authors: A
authors: Corsonello
authors: Stefania
authors: S
authors: Bandinelli
authors: Francesco
authors: F
authors: Pizzarelli
authors: Luigi
authors: L
authors: Ferrucci
authors: Raffaele Antonelli
authors: RA
authors: Incalzi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003404:Creatinine / Q000493:pharmacokinetics; D004185:Disability Evaluation; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D015233:Models, Statistical; D011237:Predictive Value of Tests
chemical_list: D003404:Creatinine