Most healthcare interventions tested in Cochrane Reviews are not effective according to high quality evidence: a systematic review and meta-analysis Dahkki Howick, J, Koletsi, D, Ioannidis, JPA, Madigan, C, Pandis, N, Loef, M, Walach, H, Sauer, S, Kleijnen, J, Seehra, J, Johnson, T, Schmidt, S