[1] Univ Palermo, Dept Surg Oncol & Oral Sci DiChirOnS, Sect Anesthesia Analgesia Intens Care & Emergency, Policlin Paolo Giaccone, Via Vespro 129, I-90127 Palermo, Italy
[2] Univ Sassari, Dept Biomed Sci, Sassari, Italy
[3] Ottawa Hosp Res Inst, Ctr Journalol, Clin Epidemiol Program, Ottawa, ON, Canada