Systematic review and meta-analysis on laparoscopic cystectomy in bladder cancer: reply letter.

We thank Tu et al. for their comments on the systematic review and meta-analysis: Systematic review and meta-analysis on laparoscopic cystectomy in bladder cancer (1). The mean difference (MD) is the difference between the mean of the experimental group and the mean of the control group, while standard mean difference (SMD) is the difference between the means of the experimental group and the control group divided by the mean standard deviation. In the paper, the weighted mean difference (WMD) and MD are used to analyze continuous variables. For the indicators with uniform units of statistical variables, MD is applied for analysis. For indicators with different units of variables, WMD is for analysis to eliminate the influence of units and to make MDs of different dimensions can be combined (2). However, there are no differences in the units of intraoperative blood loss, operation time, length of hospital stays, and usage of analgesics in the included literature, so MD is used in the main text for analysis.

In this paper, RevMan 5.3 software was used to analyze the data rate. For RevMan5.3 software, the relative risk (RR) refers to the ratio of the incidence of exposure factors in the experimental group to that in the control group. The odds ratio (OR) refers to the ratio of the exposure odds in two groups, which is the ratio of the number of cases that exposure factors occurred to that with no occurrence in the experimental group, to the ratio of the same in the control group (3). When the incidence of exposure factors studied is low, OR≈RR; therefore, RR can also be converted to OR and then merged (4). Fig. 6 in the article represents a comparison of the blood transfusion rate of patients in the two groups. Since the incidence of blood transfusion is low for the included research objects, the OR value is adopted for analysis.

The article’s supplementary files as