Grading quality of evidence and strength of recommendations for diagnostic tests and strategies - Schünemann, H; Oxman, A; Brozek, J; Glasziou, P; Jaeschke, R; Vist, G; Williams, J; Kunz, R; Craig, J; Montori, V; Bossuyt, P; Guyatt, G (BMJ Publishing Group, 2008)