Trial sequential analysis (TSA) is a recently described cumulative meta-analysis method used to weigh I and II errors and to estimate when the effect is large enough to be unlikely to be affected by further studies. The aim of this paper is to illustrate possible TSA scenarios and their significance using the meta-analyses published in the Korean Journal of Anesthesiology as a reference.
We performed a systematic research of medical literature searching for meta-analysis published in the Korean Journal of Anesthesiology. TSA was performed on each main outcome estimating the required sample size on the calculated effect size for the intervention, considering a type I error of 5% and a power of both 90% and 99%, respectively.
Six meta-analyses with a total of ten main outcomes were included in the analysis. Seven TSA confirmed the meta-analysis results. However, only three of them reached the required sample size. In two TSA the cumulative z-line lies were not statistically significant. In one TSA boundary for effect was reached with the 90% analysis but not with the 99% analysis.
In TSA the meta-analysis pooled effect may be established assessing if the cumulative sample size is large enough. TSA can be used to add strength to meta-analysis conclusions, however, pre-registration of TSA protocol is of paramount importance.
This paper could be useful to better understand the use of TSA as an additional statistical tool to improve meta-analysis quality.