Why laparoscopic adhesiolysis should not be the victim of a single randomized clinical trial

Randomized controlled trials may provide erroneous conclusions when the null hypothesis is not rejected because of insufficient analysis statistical power. The authors dispute the conclusion of a randomized controlled trial that compared chronic pain relief rates following laparoscopic adhesiolysis and diagnostic laparoscopy and recommended abandoning laparoscopic adhesiolysis. In the trial, the observed difference between pain rates (15%) was inferior to that expected (35%). On the basis of this result, we calculated the 90% confidence interval of the true difference, whose limits of -1% and 31% were found to fall outside the predetermined equivalency interval (-10% to 10%). The trial should therefore not have concluded that the 2 surgical procedures were equivalent. By doing so, it is likely that numerous surgeons have abandoned laparoscopic adhesiolysis on the basis of this statement. In any randomized trial, a calculation of statistical power is required each time that the null hypothesis cannot be rejected.

Key words: equivalency, laparoscopic adhesiolysis, number of subjects required, randomized controlled trials, statistical power