1. Department of Palliative Care, Nicolaus Copernicus University, Collegium Medicum in Bydgoszcz, Poland
2. Department of Pain Treatment and Palliative Care, Jagiellonian University College of Medicine, Cracow, Poland
3. Department of Clinical Pharmacology, Jagiellonian University College of Medicine, Cracow, Poland
4. Department of Anesthesiology and Intensive Care, Jagiellonian University College of Medicine, Cracow, Poland
5. Pain Clinic, Department of Anesthesiology and Intensive Care, Medical centre for Postgraduate Education, Warsaw, Poland