PDE5A and benign prostatic hyperplasia: Among the 7 studies, six trials were used to compare the relative IPSS's improving efficacy of different kinds of PDE5-Is with tamsulosin for the treatment of BPH-LUTS with or without ED [6, 9–13]; six trials were used to compare the relative Qmax's improving efficacy [6, 10–14]; four trials were used to compare the relative IIEF's improving efficacy [6, 10, 11, 13], and six trials were used to compare the relative safety [6, 9–13] (Figure 1).