title: Assessment of Stone Complexity for PCNL: A Systematic Review of the Literature, How Best Can We Record Stone Complexity in PCNL?
abstract: BACKGROUND
  This study aims to systematically review the literature reporting tools for scoring stone complexity and the stratification of outcomes by stone complexity. In doing so, we aim to determine whether the evidence favors uniform adoption of any one scoring system.
  
  
  METHODS
  PubMed and Embase databases were systematically searched for relevant studies from 2004 to 2014. Reports selected according to predetermined inclusion and exclusion criteria were appraised in terms of methodologic quality and their findings summarized in structured tables.
  
  
  RESULTS
  After review, 15 studies were considered suitable for inclusion. Four distinct scoring systems were identified and a further five studies that aimed to validate aspects of those scoring systems. Six studies reported the stratification of outcomes by stone complexity, without specifically defining a scoring system. All studies reported some correlation between stone complexity and stone clearance. Correlation with complications was less clearly established, where investigated.
  
  
  CONCLUSIONS
  This review does not allow us to firmly recommend one scoring system over the other. However, the quality of evidence supporting validation of the Guy's Stone Score is marginally superior, according to the criteria applied in this study. Further evaluation of the interobserver reliability of this scoring system is required.
authors.affiliation: 1 Clinical Effectiveness Unit, Royal College of Surgeons of England , London, United Kingdom .
authors.forename: John
authors.initials: J
authors.lastname: Withington
authors.affiliation: 2 Department of Urology, Addenbrookes Hospital , Cambridge, United Kingdom .
authors.forename: James
authors.initials: J
authors.lastname: Armitage
authors.affiliation: 3 Department of Urology, Norfolk and Norwich Hospital , Norwich, United Kingdom .
authors.forename: William
authors.initials: W
authors.lastname: Finch
authors.affiliation: 2 Department of Urology, Addenbrookes Hospital , Cambridge, United Kingdom .
authors.forename: Oliver
authors.initials: O
authors.lastname: Wiseman
authors.affiliation: 4 Department of Urology, Guy's and St Thomas' Hospitals Trust , London, United Kingdom .
authors.forename: Jonathan
authors.initials: J
authors.lastname: Glass
authors.affiliation: 3 Department of Urology, Norfolk and Norwich Hospital , Norwich, United Kingdom .
authors.forename: Neil
authors.initials: N
authors.lastname: Burgess
mesh_terms: D006801:Humans; D007669:Kidney Calculi / Q000473:pathology* / Q000601:surgery; D009403:Nephrostomy, Percutaneous / Q000379:methods*; D015203:Reproducibility of Results