title: Improving the performance of risk-adjusted mortality modeling for colorectal cancer surgery by combining claims data and clinical data.
abstract: OBJECTIVE
  The objective of this study was to evaluate the performance of risk-adjusted mortality models for colorectal cancer surgery.
  
  
  METHODS
  We investigated patients (n=652) who had undergone colorectal cancer surgery (colectomy, colectomy of the rectum and sigmoid colon, total colectomy, total proctectomy) at five teaching hospitals during 2008. Mortality was defined as 30-day or in-hospital surgical mortality. Risk-adjusted mortality models were constructed using claims data (basic model) with the addition of TNM staging (TNM model), physiological data (physiological model), surgical data (surgical model), or all clinical data (composite model). Multiple logistic regression analysis was performed to develop the risk-adjustment models. To compare the performance of the models, both c-statistics using Hanley-McNeil pair-wise testing and the ratio of the observed to the expected mortality within quartiles of mortality risk were evaluated to assess the abilities of discrimination and calibration.
  
  
  RESULTS
  The physiological model (c=0.92), surgical model (c=0.92), and composite model (c=0.93) displayed a similar improvement in discrimination, whereas the TNM model (c=0.87) displayed little improvement over the basic model (c=0.86). The discriminatory power of the models did not differ by the Hanley-McNeil test (p>0.05). Within each quartile of mortality, the composite and surgical models displayed an expected mortality ratio close to 1.
  
  
  CONCLUSIONS
  The addition of clinical data to claims data efficiently enhances the performance of the risk-adjusted postoperative mortality models in colorectal cancer surgery. We recommended that the performance of models should be evaluated through both discrimination and calibration.
authors.affiliation: People's Health Institution, Seoul, Korea.
authors.forename: Won Mo
authors.initials: WM
authors.lastname: Jang
authors.forename: Jae-Hyun
authors.initials: JH
authors.lastname: Park
authors.forename: Jong-Hyock
authors.initials: JH
authors.lastname: Park
authors.forename: Jae Hwan
authors.initials: JH
authors.lastname: Oh
authors.forename: Yoon
authors.initials: Y
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D015179:Colorectal Neoplasms / Q000401:mortality* / Q000601:surgery; D016208:Databases, Factual; D005260:Female; D017052:Hospital Mortality; D006784:Hospitals, Teaching; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D008962:Models, Theoretical; D009367:Neoplasm Staging; D016017:Odds Ratio; D011787:Quality of Health Care; D020379:Risk Adjustment
keywords: Colorectal neoplasms; Colorectal surgery; Quality of health care