1. Department of Anesthesia, Pain and Palliative Medicine, School of Medicine, Universidad de La Sabana, Chía, Colombia.
2. Universidad de La Sabana, Chía, Colombia.
3. IPS Cuidarte Tu Salud, Bogotá, Colombia.
4. Department of Epidemiology, School of Medicine, Universidad de La Sabana, Chía, Colombia.
5. Instituto Nacional de Cancerología, Bogotá, Colombia.
6. Department of Palliative Care and Rehabilitation Medicine, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA.