title: Comparison of sequential and fixed-sample designs in a controlled clinical trial with laparoscopic versus conventional cholecystectomy.
abstract: BACKGROUND
  The aim of this study was to compare a fixed-sample and a sequential design with regard to study duration, sample size, and medical results in a real-life situation.
  
  
  METHODS
  A randomized study comparing laparoscopic and conventional cholecystectomy was carried out with a fixed-sample design, parallel with a sequential design. The main variable was duration of postoperative convalescence.
  
  
  RESULTS
  In the fixed-sample trial the necessary number of patients was calculated to be 72. The sequential trial was conclusive after inclusion of 24 patients and reduced the duration of the study from 43 to 18 weeks. Additionally, the sequential trial reached the same conclusions as the fixed-sample trial in all the observed variables except for one.
  
  
  CONCLUSIONS
  The present study indicates that sequential design should be used more frequently in clinical trials, to involve the smallest possible number of patients necessary to reach a conclusion.
authors: Centre for Design, Administration and Statistical Analysis in Medical Research, Lillestrøm, Norway.
authors: P
authors: P
authors: Kjaersgaard
authors: O
authors: O
authors: Reiertsen
authors: E
authors: E
authors: Trondsen
authors: A R
authors: AR
authors: Rosseland
authors: S
authors: S
authors: Larsen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002763:Cholecystectomy; D017081:Cholecystectomy, Laparoscopic; D003289:Convalescence; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016032:Randomized Controlled Trials as Topic / Q000379:methods; D018401:Sample Size