title: Survival and Functional Stability in Chronic Kidney Disease Due to Surgical Removal of Nephrons: Importance of the New Baseline Glomerular Filtration Rate.
abstract: BACKGROUND
  Chronic kidney disease (CKD) can be associated with a higher risk of progression to end-stage renal disease and mortality, but the etiology of nephron loss may modify this. Previous studies suggested that CKD primarily due to surgical removal of nephrons (CKD-S) may be more stable and associated with better survival than CKD due to medical causes (CKD-M).
  
  
  OBJECTIVE
  We addressed limitations of our previous work with comprehensive control for confounding factors, differentiation of non-renal cancer-related mortality, and longer follow-up for more discriminatory assessment of the impact of CKD-S.
  
  
  METHODS
  From 1999 to 2008, 4299 patients underwent surgery for renal cancer at a single institution. The median follow-up was 9.4 yr (7.3-11.0). The new baseline glomerular filtration rate (GFR) was defined as the highest GFR between the nadir and 42 d after surgery. Three cohorts were retrospectively evaluated: no CKD (new baseline GFR >60 ml/min/1.73 m(2)); CKD-S (new baseline GFR<60 but preoperative >60 ml/min/1.73 m(2)); and CKD-M/S (new baseline and preoperative GFR both <60 ml/min/1.73 m(2)). Cohort status was permanently set at 42 d after surgery.
  
  
  METHODS
  Renal surgery.
  
  
  METHODS
  Decline in renal function (50% reduction in GFR or dialysis), all-cause mortality, and non-renal cancer mortality were examined using a multivariable Cox proportional hazards model.
  
  
  CONCLUSIONS
  CKD-M/S had a higher incidence of relevant comorbidities and the new baseline GFR was lower. On multivariable analysis (controlling for age, gender, race, diabetes, hypertension, and cardiac disease), CKD-M/S had higher rates of progressive decline in renal function, all-cause mortality, and non-renal cancer mortality when compared to CKD-S and no CKD (hazard ratio [HR] 1.69-2.33, all p<0.05). All-cause mortality was modestly higher for CKD-S than for no CKD (HR 1.19, p=0.030), but renal stability and non-renal cancer mortality were similar for these groups. New baseline GFR of <45 ml/min/1.73 m(2) significantly predicted adverse outcomes. The main limitation is the retrospective design.
  
  
  CONCLUSIONS
  CKD-S is more stable than CKD-M/S and has better survival, approximating that for no CKD. However, if the new baseline GFR is <45 ml/min/1.73 m(2), the risks of functional decline and mortality increase. These findings may influence counseling for patients with localized renal cell carcinoma and higher oncologic potential when a normal contralateral kidney is present.
  
  
  RESULTS
  Survival is better for surgically induced chronic kidney disease (CKD) than for medically induced CKD, particularly if the postoperative glomerular filtration rate is ≥45 ml/min/1.73 m(2). Patients with preexisting CKD are at risk of a significant decline in kidney function after surgery, and kidney-preserving treatment should be strongly considered in such cases.
authors.affiliation: Division of Urology, Spectrum Health, Michigan State University, Grand Rapids, MI, USA.
authors.forename: Brian R
authors.initials: BR
authors.lastname: Lane
authors.affiliation: Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Sevag
authors.initials: S
authors.lastname: Demirjian
authors.affiliation: University of California San Diego, San Diego, CA, USA.
authors.forename: Ithaar H
authors.initials: IH
authors.lastname: Derweesh
authors.affiliation: Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Toshio
authors.initials: T
authors.lastname: Takagi
authors.affiliation: Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH, USA; Department of Urology, Sun Yat-Sen University Cancer Center, Guangzhou, China.
authors.forename: Zhiling
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Lily
authors.initials: L
authors.lastname: Velet
authors.affiliation: Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Cesar E
authors.initials: CE
authors.lastname: Ercole
authors.affiliation: Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Amr F
authors.initials: AF
authors.lastname: Fergany
authors.affiliation: Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH, USA. Electronic address: campbes3@ccf.org.
authors.forename: Steven C
authors.initials: SC
authors.lastname: Campbell
mesh_terms: D000368:Aged; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007680:Kidney Neoplasms / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009399:Nephrons / Q000601:surgery*; D011183:Postoperative Complications / Q000209:etiology* / Q000401:mortality / Q000503:physiopathology*; D051436:Renal Insufficiency, Chronic / Q000209:etiology* / Q000401:mortality / Q000503:physiopathology*; D012189:Retrospective Studies; D015996:Survival Rate
keywords: Chronic kidney disease; Nephrectomy; Overall survival; Renal cell carcinoma; Renal function