title: Serum bicarbonate concentrations and kidney disease progression in community-living elders: the Health, Aging, and Body Composition (Health ABC) Study.
abstract: BACKGROUND
  In populations with prevalent chronic kidney disease (CKD), lower serum bicarbonate levels are associated with more rapid CKD progression, but whether lower bicarbonate levels also are associated with risk of incident estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m(2) and CKD progression among community-living persons with predominantly preserved kidney function is unknown.
  
  
  METHODS
  Longitudinal observational cohort study.
  
  
  METHODS
  Well-functioning community-living elders aged 70-79 years at inception.
  
  
  METHODS
  Serum bicarbonate level measured at the time of collection by arterialized venous blood sample using an arterial blood gas analyzer.
  
  
  RESULTS
  Change in eGFR over 7 years, and new eGFR < 60 mL/min/1.73 m(2) with a rate of loss of at least 1 mL/min/1.73 m(2) per year.
  
  
  METHODS
  Linear and logistic regressions were used to evaluate associations of baseline serum bicarbonate level with change in eGFR and incident eGFR < 60 mL/min/1.73 m(2).
  
  
  RESULTS
  At baseline, mean eGFR was 84 ± 16 (SD)mL/min/1.73 m(2), and serum bicarbonate level was 25.2 ± 1.9 mmol/L. Compared with participants with higher bicarbonate concentrations (23.0-28.0 mmol/L), those with bicarbonate concentrations < 23 mmol/L (n = 85 [8%]) lost eGFR0.55 (95% CI, 0.13-0.97) mL/min/1.73 m(2) per year faster in models adjusted for demographics, CKD risk factors, baseline eGFR, and urine albumin-creatinine ratio. Among the 989 (92%) participants with baseline eGFRs > 60 mL/min/1.73 m(2), 252 (25%) developed incident eGFRs < 60 mL/min/1.73 m(2) at follow-up. Adjusting for the same covariates, participants with bicarbonate concentrations < 23 mmol/L had nearly 2-fold greater odds of incident eGFRs < 60 mL/min/1.73 m(2) (OR, 1.72; 95% CI, 0.97-3.07) compared with those with higher bicarbonate concentrations.
  
  
  CONCLUSIONS
  Only 2 measurements of kidney function separated by 7 years and loss to follow-up due to intervening mortality in this elderly population.
  
  
  CONCLUSIONS
  Lower serum bicarbonate concentrations are associated independently with decline in eGFR and incident eGFR < 60 mL/min/1.73 m(2) in community-living older persons. If confirmed, serum bicarbonate levels may give insight into kidney tubule health in persons with preserved eGFRs and suggest a possible new target for intervention to prevent CKD development.
authors: Division of Nephrology and Hypertension, Department of Medicine, University of California, San Diego, CA; Nephrology Section, Veterans Affairs San Diego Healthcare System, San Diego, CA.
authors: Leonard
authors: L
authors: Goldenstein
authors: Department of Medicine, University of California, San Francisco, San Francisco, CA.
authors: Todd H
authors: TH
authors: Driver
authors: Nephrology Section, Veterans Affairs Hospital, Pittsburgh, PA; Division of Nephrology, Department of Medicine, Pittsburgh, PA; Department of Epidemiology, University of Pittsburgh, Pittsburgh, PA.
authors: Linda F
authors: LF
authors: Fried
authors: Division of Nephrology and Hypertension, Department of Medicine, University of California, San Diego, CA; Nephrology Section, Veterans Affairs San Diego Healthcare System, San Diego, CA; Division of Preventive Medicine, Department of Family and Preventive Medicine, University of California San Diego, San Diego, CA.
authors: Dena E
authors: DE
authors: Rifkin
authors: Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA.
authors: Kushang V
authors: KV
authors: Patel
authors: Division of Nephrology, Department of Medicine, University of Utah, Salt Lake City, UT.
authors: Robert H
authors: RH
authors: Yenchek
authors: Laboratory of Epidemiology and Population Sciences, National Institute on Aging, Bethesda, MD.
authors: Tamara B
authors: TB
authors: Harris
authors: Sticht Center on Aging, Wake Forest School of Medicine, Winston-Salem, NC.
authors: Stephen B
authors: SB
authors: Kritchevsky
authors: Department of Epidemiology, University of Pittsburgh, Pittsburgh, PA.
authors: Anne B
authors: AB
authors: Newman
authors: Division of Nephrology, Department of Medicine, Tufts Medical Center, Boston, MA.
authors: Mark J
authors: MJ
authors: Sarnak
authors: Department of Medicine, University of California, San Francisco, San Francisco, CA; General Internal Medicine Section, San Francisco Veterans Affairs Medical Center, San Francisco, CA; Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, CA.
authors: Michael G
authors: MG
authors: Shlipak
authors: Division of Nephrology and Hypertension, Department of Medicine, University of California, San Diego, CA; Nephrology Section, Veterans Affairs San Diego Healthcare System, San Diego, CA; Division of Preventive Medicine, Department of Family and Preventive Medicine, University of California San Diego, San Diego, CA. Electronic address: joeix@ucsd.edu.
authors: Joachim H
authors: JH
authors: Ix
mesh_terms: D000137:Acid-Base Imbalance / Q000378:metabolism; D000368:Aged; D000418:Albumins / Q000032:analysis; D001639:Bicarbonates / Q000097:blood*; D003404:Creatinine / Q000032:analysis; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D057187:Independent Living; D007677:Kidney Function Tests / Q000379:methods; D016015:Logistic Models; D008297:Male; D017063:Outcome Assessment, Health Care; D051436:Renal Insufficiency, Chronic / Q000175:diagnosis / Q000453:epidemiology / Q000378:metabolism / Q000503:physiopathology; D012307:Risk Factors; D014481:United States / Q000453:epidemiology
chemical_list: D000418:Albumins; D001639:Bicarbonates; D003404:Creatinine
keywords: Acidosis; aging; alkalosis; disease progression; kidney disease; kidney disease trajectory; renal disease; risk factor