title: Predicting conversion from laparoscopic to open cholecystectomy presented as a probability nomogram based on preoperative patient risk factors.
abstract: BACKGROUND
  We aim to develop a risk stratification tool to preoperatively predict conversion (CONV) from a laparoscopic to open cholecystectomy.
  
  
  METHODS
  Multiple risk factors were analyzed with multivariate logistic regression and presented as probability nomograms.
  
  
  RESULTS
  Of 732 patients, 47 (6.4%) required CONV. Among 40 preoperative risk factors evaluated, 5 variables were found to have significant association with CONV: 2 clinical variables, previous upper abdominal surgery (odds ratio [OR] 95.2) and obesity defined as body mass index greater than 30 kg/m(2) (OR 12.3), and 3 ultrasound parameters, visible choledocholithiasis (OR 19.8), impacted stone at the neck of the gallbladder (OR 5.9), and gallbladder wall width in millimeters (OR 2.1). Nomograms based on this multivariate model demonstrate the individual preoperative probability of CONV. Internal validation using receiver operator curve analysis showed an area under the curve of .97.
  
  
  CONCLUSIONS
  Four probability nomograms were developed as a practical individual risk stratification tool to predict probability of CONV.
authors.affiliation: Cairns Clinical School, College of Medicine and Dentistry, James Cook University, Cairns Hospital, Cairns, Queensland, Australia.
authors.forename: Janindu
authors.initials: J
authors.lastname: Goonawardena
authors.affiliation: Cairns Clinical School, College of Medicine and Dentistry, James Cook University, Cairns Hospital, Cairns, Queensland, Australia; Department of Public Health and Community Medicine, Institute of Medicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Research and Development Unit, Primary Health Care and Dental Care, Southern Älvsborg County, Region Västra Götaland, Sweden.
authors.forename: Ronny
authors.initials: R
authors.lastname: Gunnarsson
authors.affiliation: Cairns Clinical School, College of Medicine and Dentistry, James Cook University, Cairns Hospital, Cairns, Queensland, Australia; Department of Surgery, Cairns Hospital, Cairns, Queensland, Australia. Electronic address: alan.decosta@jcu.edu.au.
authors.forename: Alan
authors.initials: A
authors.lastname: de Costa
mesh_terms: D000005:Abdomen / Q000601:surgery; D000328:Adult; D000368:Aged; D002763:Cholecystectomy / Q000379:methods*; D042883:Choledocholithiasis / Q000150:complications / Q000000981:diagnostic imaging; D002769:Cholelithiasis / Q000150:complications / Q000000981:diagnostic imaging; D061887:Conversion to Open Surgery; D005260:Female; D005704:Gallbladder / Q000000981:diagnostic imaging; D006801:Humans; D010535:Laparoscopy; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D049451:Nomograms; D009765:Obesity / Q000150:complications; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D014463:Ultrasonography
keywords: Conversion; Laparoscopic cholecystectomy; Nomogram; Predict