1. Faculty of Health Sciences Catholic University San Antonio UCAM Murcia Spain
2. Spanish Back Pain Research Network Madrid Spain
3. Unidad de la Espalda Kovacs Hospital Universitario de Moncloa Madrid Spain
4. Iberoamerican Cochrane Centre Biomedical Research Institute Sant Pau (IIB Sant Pau) Barcelona Spain
5. CIBER Epidemiología y Salud Pública (CIBERESP) Madrid Spain
6. Institute of Biomedicine (IBIOMED) University of León León Spain
7. University of the Basque Country Leioa Spain