A Cochrane review [Abstract] 1 included 5 studies with a total of 166 subjects. When comparing sildenafil with placebo, investigators noted significant reduction in mortality in the sildenafil alone group (three studies, 77 participants; typical RR 0.20, 95% confidence interval (CI) 0.07 to 0.56; I2 = 0% - none; typical RR -0.36, 95% CI -0.53 to -0.18; number needed to treat for an additional beneficial outcome 3, 95% CI 2 to 6; I2 = 39% - low). Trials reported no significant differences in mortality upon comparison of the sildenafil group versus the active control group (one study, 65 participants; typical RR 0.55, 95% CI 0.05 to 5.75), or when iNO was administered to both groups (one study, 24 participants; typical RR 1.27, 95% CI 0.26 to 6.28). Physiological parameters of oxygenation (oxygenation index, partial pressure of oxygen in arterial blood (PaO2)) suggested steady improvement after the first dose of sildenafil. No clinically important side effects were reported.
Comment: The quality of evidence is downgraded by imprecise results (few patients) and by study quality (unclear allocation concealment).
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