Clinical course of COPD patients with exercise-induced elevation of pulmonary artery pressure or less severe pulmonary hypertension presenting with respiratory symptoms and the impact of bosentan intervention-prospective, single-center, randomized, parallel-group study.

"Declarations Ethics approval and consent to participateAn informed consent form describing the following items was prepared. Consent had to be obtained in writing (see Supplementary data on Procedures regarding informed consent; Supplementary information regarding Compensation in case of trial-related injury or death and Supplementary Information regarding Medical expenses). The study protocol was approved by the Ethics Committee of Nippon Medical School. All patients provided their informed consent in writing prior to their participation in this study, and the study was performed in accordance with the ethical standards of the Declaration of Helsinki (2013). Consent for publicationNot applicable’ in the declarations section. Competing interestsThe authors declare no competing interests. Competing interests The authors declare no competing interests."

"Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors."

"Trial registration This study was registered with UMIN-CTR Clinical Trial as UMIN000004749. First trial registration at 18/12/2010."