title: Renal tumour invasion index as a novel anatomical classification predicting urological complications after partial nephrectomy.
abstract: OBJECTIVE
  The goal of anatomical classification systems (ACSs) is to assess renal tumour complexity and predict surgical complications. However, the present ACSs may include some relatively unimportant components and may be complicated to use. This study introduces the invasion depth of the renal tumour divided by the parenchymal thickness, called the renal tumour invasion index (RTII), as a novel ACS and compares it with previous ACSs in predicting urological complications after partial nephrectomy.
  
  
  METHODS
  This retrospective single-institution study assessed 280 consecutive patients subjected to a planned partial nephrectomy. The main outcome was perioperative 30-day urological complications. RTII was compared with the PADUA (preoperative aspects and dimensions used for an anatomical) classification score, RENAL (radius, exophytic/endophytic, nearness to collecting system or sinus, anterior/posterior and location relative to polar lines) nephrometry score and C (centrality) index to predict urological complications, using statistical methods of receiver operating curve and logistic binary regression.
  
  
  RESULTS
  Areas under the curve for RTII, RENAL, C index and PADUA were 0.64 (95% CI 0.57-0.72, p < 0.001), 0.61 (95% CI 0.54-0.69, p = 0.004), 0.64 (95% CI 0.57-0.71, p < 0.001) and 0.57 (95% CI 0.49-0.65, p = 0.06), respectively, indicating that all the ACSs studied are able to predict urological complications. Similarly, in a multivariate logistic regression model adjusted for comorbidity and surgical approach, all ACSs were statistically significant predictors of urological complications.
  
  
  CONCLUSIONS
  RTII is as good as the previous more complicated ACSs in predicting urological complications after partial nephrectomy. As a simple measurement with a straightforward anatomical interpretation, RTII may be useful in counselling patients and stratifying patients in studies.
authors.affiliation: 1 Department of Urology, Helsinki University Central Hospital , Helsinki , Finland.
authors.forename: Harry
authors.initials: H
authors.lastname: Nisen
authors.forename: Mirja
authors.initials: M
authors.lastname: Ruutu
authors.forename: Esko
authors.initials: E
authors.lastname: Glücker
authors.forename: Harri
authors.initials: H
authors.lastname: Visapää
authors.forename: Kimmo
authors.initials: K
authors.lastname: Taari
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000145:classification / Q000473:pathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009392:Nephrectomy / Q000379:methods; D011183:Postoperative Complications / Q000453:epidemiology; D012189:Retrospective Studies; D014570:Urologic Diseases / Q000453:epidemiology