title: Surgically induced chronic kidney disease may be associated with a lower risk of progression and mortality than medical chronic kidney disease.
abstract: OBJECTIVE
  Chronic kidney disease from medical causes is present in 25% to 30% of patients before surgery for renal cancer. Although chronic kidney disease due to medical causes is typically associated with a 2% to 5% annual renal functional decline and decreased overall survival, reduced glomerular filtration rate occurring only after surgery may not have the same negative consequences.
  
  
  METHODS
  All patients undergoing surgery for suspected renal malignancy were identified in an institutional registry. Median clinical followup was 6.6 years.
  
  
  RESULTS
  Of 4,180 patients 28% had a preoperative glomerular filtration rate of less than 60 ml/minute/1.73 m(2) (chronic kidney disease due to medical causes) and in 22% the glomerular filtration rate decreased to less than 60 ml/minute/1.73 m(2) only after surgery (surgically induced chronic kidney disease). Preoperative glomerular filtration rate was a strong predictor of overall survival on univariable and multivariable analysis. The risk of death after renal surgery was 1.8, 3.5 and 4.4-fold higher in patients with preoperative chronic kidney disease stages 3, 4 and 5, respectively, vs normal preoperative glomerular filtration rate. Average overall loss of renal function was 23%, including 13% within 90 days after surgery and 3.5% annually thereafter. Postoperative glomerular filtration rate only predicted survival for patients with preexisting chronic kidney disease due to medical causes. Neither surgically induced chronic kidney disease nor postoperative glomerular filtration rate was a significant predictor of survival in patients without preexisting chronic kidney disease due to medical causes. Annual renal functional decline was 4.7% and 0.7% for patients with chronic kidney disease due to medical causes and surgically induced chronic kidney disease, respectively, with a greater than 50% reduction in glomerular filtration rate in 7.3% and 2.2%, respectively (p <0.0001). Annual renal functional decline greater than 4.0% was associated with a 43% increase in mortality (p <0.0001).
  
  
  CONCLUSIONS
  Surgically induced chronic kidney disease is associated with a relatively low risk of progressive renal functional decline and impact on survival does not appear to be substantial during intermediate term followup. In contrast, preoperative chronic kidney disease due to medical causes places patients at increased risk, indicating nephron sparing surgery for such patients.
authors.affiliation: Division of Urology, Spectrum Health, Michigan State University, Grand Rapids, Michigan, USA.
authors.forename: Brian R
authors.initials: BR
authors.lastname: Lane
authors.forename: Steven C
authors.initials: SC
authors.lastname: Campbell
authors.forename: Sevag
authors.initials: S
authors.lastname: Demirjian
authors.forename: Amr F
authors.initials: AF
authors.lastname: Fergany
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009392:Nephrectomy / Q000009:adverse effects*; D051436:Renal Insufficiency, Chronic / Q000209:etiology* / Q000401:mortality*; D012189:Retrospective Studies; D018570:Risk Assessment; D055815:Young Adult