This document discusses several issues that undermine confidence in published medical research: 1. Poor methodology, selective reporting, and biased interpretation of results are common problems. 2. Reporting is often inadequate, omitting key details about how studies were designed and conducted. 3. Peer review is limited and cannot guarantee scientifically sound papers. Readers should be cautious in their interpretation.

1. How much confidence can we have in published medical research? Doug Altman Centre for Statistics in Medicine University of Oxford

11. Wenzel et al, NEJM 2004

12. Wenzel et al, NEJM 2004 No mention in Methods of planning to look at subgroups Comparison of P values is wrong No significant difference between 3 groups (interaction test)

14. [Chan et al, JAMA 2004]

19. Doyle et al, Arch Surg 2008

20. “ Patients who undergo liver transplantation at age 60 or above have 1-year and 5-year survival rates similar to those of younger patients …” No mention that the study was of hepatitis C positive patients

39. STROBE

41. Perrone et al, Eur J Cancer 2008

42. Perrone et al, Eur J Cancer 2008

44. www.equator-network.org

48. Reproducible research