Current treatments for pulmonary arterial hypertension (PAH) have been shown to improve dyspnea, 6-min walk distance (6MWD), and pulmonary hemodynamics, but few studies were designed to compare treatment regimens or assess the impact of treatment on mortality.
We conducted a systematic review to evaluate the comparative effectiveness and safety of monotherapy or combination therapy for PAH using endothelin receptor antagonists, phosphodiesterase inhibitors, or prostanoids. We searched English-language publications of comparative studies that reported intermediate or long-term outcomes associated with drug therapy for PAH. Two investigators abstracted data and rated study quality and applicability.
We identified 28 randomized controlled trials involving 3,613 patients. We found no studies that randomized treatment-naive patients to monotherapy vs combination therapy. There was insufficient statistical power to detect a mortality difference associated with treatment. All drug classes demonstrated increases in 6MWD when compared with placebo, and combination therapy showed improved 6MWD compared with monotherapy. For hospitalization, the OR was lower in patients taking endothelin receptor antagonists or phosphodiesterase-5 inhibitors compared with placebo (OR, 0.34 and 0.48, respectively).
Although no studies were powered to detect a mortality reduction, monotherapy was associated with improved 6MWD and reduced hospitalization rates. Our findings also suggest an improvement in 6MWD when a second drug is added to monotherapy.