title: Decline in kidney function before and after nephrology referral and the effect on survival in moderate to advanced chronic kidney disease.
abstract: BACKGROUND
  The burden of chronic kidney disease (CKD) is high, but its natural history and the benefit of routine nephrology care is unclear. This study investigated the decline in kidney function prior to and following nephrology referral and its association with mortality.
  
  
  METHODS
  This study provides a retrospective review of the individual rates of glomerular filtration rate (GFR) decline (millilitre per minute per 1.73 m(2)/year) for the 5 years before and after referral in 726 new referrals with stages 3-5 CKD to one renal unit between 1997 and 2003. Blood pressures are averages at referral, 1 and 3 years post referral. Logistic regression and Cox's models tested factors predicting post-referral GFR decline and the impact on mortality.
  
  
  RESULTS
  Mean (SD) age was 72 (14), and 389 (54%) patients had stages 4-5 CKD. GFR decline slowed significantly from -5.4 ml/min/1.73 m(2)/year (-13. to -2) before to -0.35 ml/min/1.73 m(2)/year (-3 to +3) after referral (P < 0.001). Blood pressure also reduced significantly (155/84 to 149/80, P < 0.05) with most changes occurring within 1 year of referral. Factors predicting a non-progressive post-referral decline included a lower systolic blood pressure at referral and 1 year after referral, a CKD diagnosis other than diabetic nephropathy, less baseline proteinuria and a non-progressive pre-referral GFR decline. A non-progressive post-referral GFR decline was independently associated with significantly better survival (hazard ratio 0.55, 95% CI 0.40-0.75, P <or = 0.001) after adjustment for known risk factors.
  
  
  CONCLUSIONS
  Following nephrology referral, GFR decline slowed significantly and was associated with better survival. Earlier detection of patients with progressive CKD and interventions to slow progression may have benefits on both kidney and patient survival.
authors.affiliation: Department of Public Health Sciences and Medical Statistics, University of Southampton, Level C(805), South Academic Block, Southampton General Hospital, Tremona Road, Southampton, UK. chris@soton.ac.uk
authors.forename: Chris
authors.initials: C
authors.lastname: Jones
authors.forename: Paul
authors.initials: P
authors.lastname: Roderick
authors.forename: Scott
authors.initials: S
authors.lastname: Harris
authors.forename: Mary
authors.initials: M
authors.lastname: Rogerson
mesh_terms: D000368:Aged; D001794:Blood Pressure; D002908:Chronic Disease; D003928:Diabetic Nephropathies / Q000150:complications / Q000453:epidemiology; D018450:Disease Progression; D042241:Early Diagnosis; D004739:England / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000453:epidemiology; D007668:Kidney / Q000503:physiopathology*; D007674:Kidney Diseases / Q000150:complications / Q000175:diagnosis / Q000628:therapy; D007676:Kidney Failure, Chronic / Q000453:epidemiology / Q000209:etiology / Q000628:therapy; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009398:Nephrology; D016016:Proportional Hazards Models; D012017:Referral and Consultation / Q000706:statistics & numerical data*; D017582:Renal Replacement Therapy / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012307:Risk Factors; D016019:Survival Analysis; D013997:Time Factors