title: Dietary acid intake and kidney disease progression in the elderly.
abstract: OBJECTIVE
  Non-volatile acid is produced by metabolism of organic sulfur in dietary protein, and promotes kidney damage. We investigated the role of dietary acid load, in terms of net endogenous acid production (NEAP), in chronic kidney disease (CKD) progression.
  
  
  METHODS
  217 CKD patients on low-protein diet with a normal serum bicarbonate level were enrolled in this retrospective cohort study in Japan. The primary outcome was 25% decline in estimated glomerular filtration rate (eGFR) or start of dialysis. Their NEAP was measured every 3 months. The patients were categorized into four groups on the basis of quartiles of NEAP every 3 months. The groups were treated as time-dependent variables.
  
  
  RESULTS
  The average age (SD) was 70.6 (7.1) years; eGFR 23.5 (14.2) ml/min/1.73 m(2). Analysis using extended Cox models for the NEAP groups adjusted for baseline characteristics (referring to group 1 showing the lowest NEAP) showed that high NEAP was associated with a high risk of CKD progression; group 2, adjusted hazard ratio (HR) 3.930 (95% confidence interval (CI) 1.914, 8.072); group 3, adjusted HR 4.740 (95% CI 2.196, 10.288); group 4, adjusted HR 4.303 (95% CI 2.103, 8.805). Logistic regression analysis adjusted for baseline characteristics showed that the occurrence of hypoalbuminemia or hyperkalemia was associated with low serum bicarbonate level and the presence of complications at baseline, but not with NEAP.
  
  
  CONCLUSIONS
  In elderly CKD patients, our findings suggest that high NEAP is independently associated with CKD progression. The decrease in NEAP may be an effective kidney-protective therapy.
authors: Department of Nephrology, Tokyo Kyosai Hospital, Tokyo, Japan.
authors: Eiichiro
authors: E
authors: Kanda
authors: Masumi
authors: M
authors: Ai
authors: Renjiro
authors: R
authors: Kuriyama
authors: Masayuki
authors: M
authors: Yoshida
authors: Tatsuo
authors: T
authors: Shiigai
mesh_terms: D000143:Acids / Q000378:metabolism*; D000368:Aged; D001639:Bicarbonates / Q000378:metabolism; D018753:Diet, Protein-Restricted; D004044:Dietary Proteins / Q000493:pharmacokinetics*; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D006435:Renal Dialysis; D051436:Renal Insufficiency, Chronic / Q000178:diet therapy* / Q000378:metabolism* / Q000503:physiopathology; D012189:Retrospective Studies; D018570:Risk Assessment
chemical_list: D000143:Acids; D001639:Bicarbonates; D004044:Dietary Proteins