1. Clinical Operational Research Unit, University College London, London, UK.
2. Clinic for Thoracic Surgery, Institute for Pulmonary Diseases of Vojvodina, University of Novi Sad, Serbia
3. Department of Thoracic Surgery, Policlinico Hospital Catania, University of Catania, Catania, Italy
4. Clinical Trials & Evaluation Unit, Royal Brompton & Harefield NHS Foundation Trust, London, UK