Clinical Evidence published by the British Medical Journal (2007) analyzed common medical treatments to evaluate which are supported by sufficient reliable evidence.
A reviewed of approximately 2,500 medical treatments showed that:
- 13 percent were found to be beneficial
- 23 percent were likely to be beneficial
- 8 percent were as likely to be harmful as beneficial
- 6 percent were unlikely to be beneficial
- 4 percent were likely to be harmful or ineffective.
- 46 percent were unknown whether they were efficacious or harmful.
In the late 1970s, the US government conducted a similar evaluation and found a strikingly similar result. They found that only 10 percent to 20 percent of medical treatment had evidence of efficacy (Office of Technology Assessment, 1978).