1 Iberoamerican Cochrane Centre - Biomedical Research Institute Sant Pau (IIB Sant Pau), Barcelona, Spain. Electronic address: laura.martinez.garcia@cochrane.es.
2 Iberoamerican Cochrane Centre - Biomedical Research Institute Sant Pau (IIB Sant Pau), Barcelona, Spain.
3 Iberoamerican Cochrane Centre - Biomedical Research Institute Sant Pau (IIB Sant Pau), Barcelona, Spain; CIBER de Epidemiología y Salud Pública (CIBERESP), Spain.