Comments on “Laparoscopic Cholecystectomy Under Spinal Versus General Anesthesia: A Prospective,Randomized Study”—Can You Really Have the Conclusion?

Dear Editor:

We write with reference to the article entitled “Laparoscopic Cholecystectomy Under Spinal Versus General Anesthesia: A Prospective, Randomized Study” by Samer S. Bessa et al. ¹ A majority of previous studies have researched the use of spinal or general anesthesia in laparoscopic cholecystectomy.^2,3 Bessa et al. have reported that laparoscopic cholecystectomy performed under spinal anesthesia is feasible, safe, and associated with significantly less early postoperative pain, compared with that performed under general anesthesia.

Although the authors are to be commended for their aim to conduct a prospective, randomized trial about the effect of spinal versus general anesthesia in laparoscopic cholecystectomy, there are some issues with both the design of the study and the statistical analysis used. As for study design, the major problem is that there is no reference to any sample size calculation. In fact, for a particular finding to be claimed as significant (or not), the study should be powered enough. ⁴ In this article, the authors do not state anything about the expected change in visual analog scale, postoperative complications, and analgesic requirements. Therefore, it is almost impossible to perform a prestudy sample size calculation (at least, we could not). It is almost impossible to perform a post hoc sample size calculation or power analysis on the statistical tests that the authors have used. However, given the significant overlap of visual analogue scale scores in the groups (see Table 2), a total sample of 60 patients might not have been sufficient to make inferences with a real significance (e.g., considering the “standard,” an error of 0.05 and a power of 0.08). As the authors do actually draw conclusions from their data, could they really confirm the correctness of their sample size calculation or provide the power and level of significance of each test given a total sample of 60 patients? So we think that the study requires much larger numbers before any significant conclusions may be demonstrated.

Although this study is extremely interesting for those physicians involved in the management of laparoscopic cholecystectomy, appropriate statistical analysis of data from trials is crucial to draw adequate conclusions. We hope our suggestions will be useful to authors who will be involved in similar studies in the future.