Comparison of Sequential and Fixed-Sample Designs in a Controlled Clinical Trial with Laparoscopic versus Conventional Cholecystectomy

Abstract

Kjærsgaard P, Reiertsen CTrondsen E, Rosseland AR, Larsen S. Comparison of sequential and fixed-sample designs in a controlled clinical trial with laparoscopic versus conventional cholecystectomy. Scand J Gastroenterol 1994;29:854-858.

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. Conclusion: 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.

Key Words:

• Conventional cholecystectomy
• double triangular test
• fixed-sample clinical trial
• laparoscopic cholecystectomy
• sequential clinical trial