Related Experiment Video
Updated: Jun 14, 2026
A Clinical Trial Assessing the Safety, Efficacy, and Delivery of Olive-Oil-Based Three-Chamber Bags for Parenteral Nutrition
Published on: September 20, 2019
Reported effects in randomized controlled trials were compared with those of nonrandomized trials in cholecystectomy
Dirk Müeller1, Stefan Sauerland, Edmund A M Neugebauer
1Institute for Research in Operative Medicine, University Witten/Herdecke, Cologne, Germany. dirkwmueller@gmx.de
Objectives:
Because external validity of randomized controlled trials (RCTs) may be insufficient, the performance of nonrandomized controlled trials (nRCTs) is increasingly debated. RCTs and nRCTs were compared using the example of laparoscopic vs. open cholecystectomy (LC vs. OC).
Study Design And Setting:
RCTs and nRCTs comparing LC and OC were identified by searching PubMed. To assess internal and external validity of the studies, patient characteristics, relative risks, and mean differences of RCTs and nRCTs were compared by meta-analytic techniques.
Results:
In total, 162 studies were analyzed (136 nRCTs and 26 RCTs). Significant discrepancies between RCT- and nRCT-based results were revealed for 3 of 15 variables: overall complications (P<0.021), wound infections (P<0.014), and length of hospital stay (P<0.005). In RCTs and in nRCTs, length of hospital stay and return to work were significantly reduced when using LC compared with OC. The results of nRCTs were more often heterogeneous among themselves (11 of 15) as compared with RCTs (4 of 15).
Conclusion:
The results of RCTs and nRCTs differ significantly in at least 20% of the variables. External validities of RCTs and nRCTs in LC vs. OC appear to be similar. Between-study heterogeneity was larger in nRCTs than in RCTs of cholecystectomy.
