We read with great interest the meta-analysis by Du et al. [Citation1] that assessed the efficacy and safety of a new oral phosphodiesterase type 5 inhibitors (PDE5-Is), mirodenafil, for patients with erectile dysfunction (ED). The meta-analysis identified three randomized controlled trials (RCTs) [Citation2–4] including 374 participants and concluded that mirodenafil is effective and well-tolerated therapy for ED. However, the main issue needed to be addressed is that whether it is reasonable to simply integrate data from the three RCTs. Participants in one trial [Citation3] are ED patients who are taking antihypertensive medications at the same time, which is quite different from another two trials [Citation2,Citation4]. When we tried to find out whether the trial by Paick et al. [Citation3] met the inclusion criteria of this meta-analysis, we found that the inclusion criteria cared more about the patients. However, inclusion criteria for meta-analysis should be focused more on study, which means studies that meet the inclusion criteria and are included in the meta-analysis but not the patients [Citation5].
ED has a multifactorial etiology and PDE5-Is are widely used to treat the disease. However, certain types of antihypertensive agents are likely to affect the efficacy of PDE5-Is in ED patients and even antihypertensive drug itself can impact some aspects of sexual function [Citation6–8]. Angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, calcium channel blockers and alpha-blockers are less likely to cause ED while thiazide diuretics and some less selective beta-blockers (atenolol and carvedilol) may be detrimental to ED [Citation9]. Antihypertensive medications used in Paick’s trial included almost all types and near half of subjects in the trial took more than two types of antihypertensive drug to control their blood pressure. Hence, conclusion from the trial can only be for the ED patients taking antihypertensive medication. Meanwhile, integrating data from the three trials in this meta-analysis seems to be unreasonable and might overestimate the efficacy of mirodenafil for ED patients.
Declaration of interest
The authors report no conflicts of interest to declare.
References
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