title: Non-randomised patients in a cholecystectomy trial: characteristics, procedures, and outcomes.
abstract: BACKGROUND
  Laparoscopic cholecystectomy is now considered the first option for gallbladder surgery. However, 20% to 30% of cholecystectomies are completed as open operations often on elderly and fragile patients. The external validity of randomised trials comparing mini-laparotomy cholecystectomy and laparoscopic cholecystectomy has not been studied. The aim of this study is to analyse characteristics, procedures, and outcomes for all patients who underwent cholecystectomy without being included in such a trial.
  
  
  METHODS
  Characteristics (age, sex, co-morbidity, and ASA-score), operation time, hospital stay, and mortality were compared for patients who underwent cholecystectomy outside and within a randomised controlled trial comparing mini-laparotomy and laparoscopic cholecystectomy.
  
  
  RESULTS
  During the inclusion period 1719 patients underwent cholecystectomy. 726 patients were randomised and 724 of them completed the trial; 993 patients underwent cholecystectomy outside the trial. The non-randomised patients were older--and had more complications from gallstone disease, higher co-morbidity, and higher ASA--score when compared with trial patients. They were also more likely to undergo acute surgery and they had a longer postoperative hospital stay, with a median 3 versus 2 days (p < 0.001 for all comparisons). Standardised mortality ratio within 90 days of operation was 3.42 (mean) (95% CI 2.17 to 5.13) for non-randomised patients and 1.61 (mean) (95%CI 0.02 to 3.46) for trial patients. For non-randomised patients, operation time did not differ significantly between mini-laparotomy and open cholecystectomy in multivariate analysis. However, the operation for laparoscopic cholecystectomy lasted 20 minutes longer than open cholecystectomy. Hospital stay was significantly shorter for both mini-laparotomy and laparoscopic cholecystectomy compared to open cholecystectomy.
  
  
  CONCLUSIONS
  Non-randomised patients were older and more sick than trial patients. The assignment of healthier patients to trials comparing mini-laparotomy cholecystectomy and laparoscopic cholecystectomy limits the external validity of conclusions reached in such trials.
authors.affiliation: Department of Surgery, University Hospital of Umeå, Sweden. axel.ros@lj.se
authors.forename: Axel
authors.initials: A
authors.lastname: Ros
authors.forename: Per
authors.initials: P
authors.lastname: Carlsson
authors.forename: Mikael
authors.initials: M
authors.lastname: Rahmqvist
authors.forename: Karin
authors.initials: K
authors.lastname: Bäckman
authors.forename: Erik
authors.initials: E
authors.lastname: Nilsson
mesh_terms: D000328:Adult; D017081:Cholecystectomy, Laparoscopic / Q000401:mortality; D041761:Cholecystolithiasis / Q000453:epidemiology / Q000601:surgery; D015897:Comorbidity; D005260:Female; D006801:Humans; D007902:Length of Stay; D008297:Male; D018579:Patient Selection; D011446:Prospective Studies; D016032:Randomized Controlled Trials as Topic; D012044:Regression Analysis; D015203:Reproducibility of Results; D012107:Research Design