1 Iberoamerican Cochrane Centre, Biomedical Research Institute Sant Pau (IIB Sant Pau), Carrer Sant Antoni Maria Claret, 167, Pavelló 18, Ground Floor, Barcelona 08025, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Spain.
2 Iberoamerican Cochrane Centre, Biomedical Research Institute Sant Pau (IIB Sant Pau), Carrer Sant Antoni Maria Claret, 167, Pavelló 18, Ground Floor, Barcelona 08025, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Spain; Department of Clinical Epidemiology & Biostatistics, McMaster University, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada. Electronic address: palonso@santpau.cat.