title: Improving the quality of liver resection: a systematic review and critical analysis of the available prognostic models.
abstract: BACKGROUND
  Liver resection is considered to offer the only hope of cure for patients with liver malignancy. However, there are concerns about its safety, particularly in view of the increasing efficacy of less invasive strategies. No systematic review of prognostic research in liver resections has yet been performed.
  
  
  METHODS
  A systematic search identified articles published between 1999 and 2012 that performed a risk prediction analysis in patients undergoing liver resection. Studies were included if an outcome occurring within 90 days of surgery was identified, multivariable analysis performed and regression coefficients provided. The main endpoints were the outcomes and predictors chosen by the investigators, their definition, the performance and validity of the models, and the quality of the study as assessed using the QUIPS (quality in prognosis studies) tool.
  
  
  RESULTS
  A total of 91 studies were included. Eleven were prospective, but only two of these were registered. Twenty-eight endpoints were identified. These focused on postoperative morbidity or mortality, but many were redundant or ill defined and other relevant patient-reported outcomes were lacking. Predictors were not standardized, were poorly defined and overlapped. Only nine studies assessed the performance of their models and seven made an internal or temporal validation, but none reported an external validation or impact analysis. The median QUIPS score was 34 out of 50, indicating a high risk for bias.
  
  
  CONCLUSIONS
  Prognostic research in liver resection is still at the developmental stage.
authors.affiliation: Department of Surgery, Assistance Publique Hôpitaux de Paris (AP-HP), Henri Mondor Hospital, Faculty of Medicine, University of Paris Est, Creteil, France.
authors.forename: Chetana
authors.initials: C
authors.lastname: Lim
authors.forename: Cornelius H
authors.initials: CH
authors.lastname: Dejong
authors.forename: Oliver
authors.initials: O
authors.lastname: Farges
mesh_terms: D018572:Disease-Free Survival; D005260:Female; D006498:Hepatectomy / Q000009:adverse effects* / Q000379:methods; D006801:Humans; D008113:Liver Neoplasms / Q000175:diagnosis / Q000401:mortality* / Q000601:surgery*; D008297:Male; D020380:Needs Assessment; D011183:Postoperative Complications / Q000401:mortality* / Q000503:physiopathology / Q000628:therapy; D011379:Prognosis; D058996:Quality Improvement; D018570:Risk Assessment; D016019:Survival Analysis