Unexpected difficulties in randomizing patients in a surgical trial: a prospective study comparing extracorporeal shock wave lithotripsy with open cholecystectomy.

Shortly after extracorporeal shock wave lithotripsy (ESWL) was introduced as a promising new treatment modality for gallstone disease, a randomized controlled study was performed to assess the cost-effectiveness of ESWL compared to open cholecystectomy, the gold standard. During the performance of this study it was found that during a 3-year intake period only 8.3% (37 of 448) of the patients could be entered into the trial. Three factors were identified that hampered patient accrual: (1) restricted eligibility for ESWL (and thus for the study), which could not have been predicted on the data provided in the literature; (2) the introduction of laparoscopic cholecystectomy; and (3) strong patient preference, inhibiting randomization. All three mechanisms could not have been predicted during the design phase of the study. It is concluded that it is not always feasible to conduct a randomized study in surgery due to unforeseen circumstances. Entering patients into surgical trials is difficult in quickly evolving fields of surgery, such as the management of gallstone disease. Acquiring informed consent is also difficult when treatment characteristics are divergent. A randomized controlled study on the effects of laparoscopic cholecystectomy will therefore probably never be performed.