Table 2 World Health Organization functional class (WHO FC) IV patients in randomised clinical trials of pulmonary arterial hypertension

Investigational drug	Trial and publication year	Patients in WHO FC IV at baseline %
Epoprostenol	Barst et al. [20]; 1996	27
Iloprost^#	Olschewski et al. [39]; 2002	42
Treprostinil	Simonneau et al. [40]; 2002	7
Bosentan	Channick et al. [41] (Study 351); 2001	0
	Rubin et al. [42] (BREATHE-1); 2002	8
Ambrisentan	Galiè et al. [43] (ARIES-1); 2008	7
	Galiè et al. [43] (ARIES-2); 2008	2
Sitaxentan	Barst et al. [44] (STRIDE-1); 2004	1
	Barst et al. [45] (STRIDE-2); 2006	4
Sildenafil	Galiè et al. [46] (SUPER-1); 2005	3
Tadalafil	Galiè et al. [47] (PHIRST-1); 2009	2

BREATHE: Bosentan Randomized Trial of Endothelin Antagonist Therapy; ARIES: Ambrisentan in Pulmonary Arterial Hypertension, Randomized, Double-Blind, Placebo-Controlled, Multicenter, Efficacy Study; STRIDE: Sitaxsentan To Relieve Impaired Exercise; SUPER: Sildenafil Use in Pulmonary Arterial Hypertension; PHIRST: Pulmonary Arterial Hypertension and Response to Tadalafil. ^#: patients were stratified by WHO FC prior to being randomised.