Trial sequential analysis (TSA)

Because of systematic errors and random errors caused by sparse data and repetitive testing, conventional meta-analyses of cumulative trails may include false positive results (type I errors) and false negative results (type II errors).²⁸ Trial sequential analysis (TSA) is a tool for quantifying the statistical reliability of data to overcome these limitations of traditional meta-analyses. Therefore, TSA was performed to control for random errors and to assess the required sample information.²⁹ In TSA, we generated the cumulative Z-curve of each study and assessed their crossing Z-value as 1.96 (P = 0.05), as well as the trial sequential monitoring boundaries. To calculate the optimal information size, type I error was set at 5% and type II error was set at 20%. The TSA was conducted by TSA program (TSA version 0.9 beta software, Copenhagen Trial Unit 2011, http://www.ctu.dk/tsa).