Response to Letter to the Editor: Meta-Analysis of the Long-term Efficacy and Tolerance of Tadalafil Daily Compared With Tadalafil On-Demand in Treating Men With Erectile Dysfunction.

Dear Editor,

I am very glad to hear from you. Thank you again for your acceptance of our article. I am also very glad to receive letters from readers.

First of all, we cannot agree with the reader, and we will explain each of them below.

The reader said, "In the results section, the authors reported that the tadalafil daily group had a greater increase of IIEF-EF (MD = 1.24; 95% CI = 0.03–2.44; P = 0.04), SEP2 (MD - 10.08; 95% CI = 9.15–11.01; P < 0.00001) and SEP3 (MD - 8.19; 95% CI = 2.09–14.29; P < 0.00001) in comparison to tadalafil on-demand, which suggest the superiority of tadalafil daily. However, when we show the results using the forests plots figures, it could be interpreted as the other way due to technical setting of describing forest plot."

We think the reader's understanding of forest plot figures is flawed. How to interpret the forests plots, we suggest the author to refer to the principles of RevMan, version 5.3.0 (Cochrane Collaboration, Oxford, UK). Maybe the author's drawing style is different from that of our team's.

The IIEF-EF scores were theoretically categorized into the following ED severity categories: severe (0–10), moderate (11–16), mild (17–25), and normal (26–30). The lower scores of the IIEF indicated more severe symptoms.

For example, for the IIEF-EF, we studied and analyzed the variation, and the larger the increase, the more effective the treatment. Almost all studies included in the analysis of the IIEF-EF showed that the tadalafil daily group had a greater increase of the IIEF-EF score in comparison with the tadalafil on-demand group. This result was also the same as that of our study by the analysis of forest plots. It was worth considering that the reader could come to the opposite conclusion, similarly for SEP 2 and SEP 3 too.

We were also aware of the limitations of this article and explained it during the discussion. In addition, a limitation of this study was not considering placebo effect. Subjective measurement outcomes should be interpreted more thoroughly. We look forward to more meta-analysis to explore the efficacy and tolerance of tadalafil daily, tadalafil on demand, and placebo in treating erectile dysfunction after at least 6 months of treatment cycle.

Statement of authorship

Conception and Design

Yuanshan Cui

Acquisition of Data

Zhongbao Zhou, Zhenli Gao

Analysis and Interpretation of Data

Zhongbao Zhou, Zhenli Gao, Jitao Wu

Drafting the Article

Zhongbao Zhou

Revising It for Intellectual Content

Zhenli Gao, Jitao Wu, Yuanshan Cui

Final Approval of the Completed Article

Zhongbao Zhou, Zhenli Gao, Jitao Wu, Yuanshan Cui