title: Surveillance for hepatocellular carcinoma: development and validation of an algorithm to classify tests in administrative and laboratory data.
abstract: BACKGROUND
  The purpose of alpha-fetoprotein (AFP) and abdominal ultrasound (US) cannot be discerned in administrative data.
  
  
  OBJECTIVE
  We developed an algorithm to identify AFP and US used as surveillance tests for hepatocellular carcinoma (HCC).
  
  
  METHODS
  We evaluated 300 AFP and 301 US tests from a VA database. Surveillance predictors in the administrative files (diagnoses, labs) were examined in logistic regression models. We calculated model-based probabilities of HCC surveillance status, and developed classification procedures using single and multiple imputation methods.
  
  
  RESULTS
  The predictors of surveillance intent for AFP were absence of alcoholism, abdominal pain, ascites, diabetes and high AST levels. For US, the predictors of surveillance were prior AFP testing and HIV status and absence of abdominal pain, ascites, or drug dependence. For AFP classification, single imputation compared favorably with multiple imputation, both showing robustness in discrimination and calibration. For US both approaches were less robust in discrimination and calibration which was more moderate in multiple imputation than single imputation.
  
  
  CONCLUSIONS
  Predictive algorithms in administrative files can be used to identify AFP performed for HCC surveillance, however, the intent of US is more difficult to identify.
authors.affiliation: Section of Health Services Research, Houston Center for Quality of Care & Utilization Studies, The Houston Veterans Affairs Medical Center and Baylor College of Medicine, Houston, TX, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Richardson
authors.forename: Louise
authors.initials: L
authors.lastname: Henderson
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Davila
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Kramer
authors.forename: Conar P
authors.initials: CP
authors.lastname: Fitton
authors.forename: G John
authors.initials: GJ
authors.lastname: Chen
authors.forename: Hashem B
authors.initials: HB
authors.lastname: El-Serag
mesh_terms: D000465:Algorithms; D002138:Calibration; D006528:Carcinoma, Hepatocellular / Q000175:diagnosis* / Q000000981:diagnostic imaging; D006801:Humans; D016013:Likelihood Functions; D008113:Liver Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging; D016015:Logistic Models; D011159:Population Surveillance; D012372:ROC Curve; D014463:Ultrasonography; D000509:alpha-Fetoproteins / Q000032:analysis
chemical_list: D000509:alpha-Fetoproteins