Sequential clinical trials in emergency medicine

In a traditional clinical trial, a fixed number of patients are evaluated before the data are analyzed. This has the disadvantage that more patients may be enrolled than are necessary to achieve a statistically significant result. Sequential statistical techniques provide a method for the analysis of clinical trials so that a reliable result is obtained with a minimum number of patients. In a sequential trial, the data are analyzed after each patient's outcome is known, and the trial is halted as soon as treatment efficacy or lack thereof is demonstrated. This study was undertaken to confirm the advantages of sequential statistical techniques over conventional fixed-sample-size statistical techniques for the analysis of clinical trials. Using sequential techniques, we conducted computer simulations of two fixed-sample-size clinical studies from the literature - a trial of hepatitis B vaccine in homosexual men (N Engl J Med 1980;303:833-841) and a trial of the pneumatic antishock garment in hypotensive patients with penetrating abdominal trauma (Ann Emerg Med 1987;16:653-658). In the trial simulations, patients were randomly assigned to the control and test groups, their outcomes were determined randomly according to the frequency of outcomes observed in the actual studies, and the simulated sequential studies were continued until conclusions were reached. Thousands of possible realizations of each trial were simulated; thus, the distribution of required patient numbers was determined.(ABSTRACT TRUNCATED AT 250 WORDS)