GRADE guidelines: 12. Preparing summary of findings tables-binary outcomes. por Guyatt, G, Oxman, A, Santesso, N, Helfand, M, Vist, G, Kunz, R, Brozek, J, Norris, S, Meerpohl, J, Djulbegovic, B, Alonso-Coello, P, Post, P, Busse, J, Glasziou, P, Christensen, R, Schünemann, H