Arif et al. showed, in patients with COPD-related PAH, that PDE-5 inhibitors significantly decreased sPAP (pooled treatment effect 5.9 mm Hg; 95% CI −10.3, −1.6, p = 0.007), but had inconsistent clinical benefits [25]. This evidence concerns the gene PDZK1IP1 and pulmonary arterial hypertension.