Randomised, placebo-controlled trials, reporting data at baseline and after 12 to 18 weeks, of treatment for pulmonary arterial hypertension were eligible for inclusion in the review.
Most trials were of 12 week duration, with the remainder ranging from 16 to 52 weeks duration. Included trials compared placebo against a range of active treatments (prostacyclin analogues, endothelin receptor antagonists, a thromboxane synthetase inhibitor and a phosphodiesterase inhibitor).
Participants in the placebo study arms were predominately women (76%), aged on average 47.4 (standard deviation 4.8) years, in New York Heart Association/World Health Organization functional class III (68.9%). The most common aetiologies were idiopathic pulmonary arterial hypertension (56.8%) and connective tissue disease associated pulmonary arterial hypertension (24.2%).
The included trials reported a range of mortality, morbidity, functional and haemodynamic outcomes. Functional and haemodynamic outcomes included: six-minute walk distance, mean pulmonary artery pressure, pulmonary vascular resistance, cardiac index, mixed venous oxygen saturation, and Borg dyspnoea score.
The authors did not state how many reviewers performed the selection.