Bosentan in Patients With Inoperable Chronic Thromboembolic Pulmonary Hypertension (CTEPH)

Change From Baseline to All Assessed Time Points in 6-minute Walk Test (6MWT) Distance

Exercise capacity was assessed using the 6MWT. Area used for testing had to be a minimum of 30m in length and 2-3m in width, with 3m gradations. Areas were well ventilated with air temperature controlled. The test was administered at the same time of day and by the same tester throughout the study. The tester measured the distance walked by non-encouraged patients during the timed 6min period. If the test was stopped before 6 minutes, the main reason for stopping the test was recorded. The tester measured the distance walked by patients during the timed 6min period.

Time frame: Until discontinuation of study drug, up to 3.3 years

Change From Baseline to All Assessed Time Points in Borg Dyspnea Index

Maximal dyspnea during the walk test was assessed by the patient using the Borg dyspnea index. Immediately following each walk test, patients rated perceived maximal breathlessness during the walk test on a 12-point scale (0 \[nothing at all\], 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 \[maximum ever experienced\]).

Time frame: Until discontinuation of study drug, up to 3.3 years

Disease Severity - Number of Patients Showing Improvement by One Class or More in World Health Organisation (WHO) Functional Classification of Pulmonary Hypertension (PH)

Disease severity was assessed by WHO classification of PH criteria: Class I: no limitation of physical activity (PA). Ordinary PA: no undue dyspnea/fatigue, chest pain, near syncope. Class II: slight limitation of PA. Comfortable at rest. Ordinary PA: undue dyspnea/fatigue, chest pain, near syncope. Class III: marked limitation of PA. Comfortable at rest. Less than ordinary PA: undue dyspnea/fatigue, chest pain, near syncope. Class IV: inability to carry out PA without symptoms. Right heart failure. Dyspnea/fatigue may even have been present at rest. Discomfort increased by any PA.

Time frame: Until discontinuation of study drug, up to 3.3 years

Time to Clinical Worsening up to End-of-study

An event of clinical worsening was defined as death during the treatment period, a treatment-emergent adverse event that led to permanent discontinuation of study treatment and with outcome death, hospitalization due to worsening pulmonary hypertension, or lung transplantation. Patients are censored at 1 day after the end of treatment or at day of pulmonary endarterectomy if earlier.