Evidence Based
Medicine
Level Rating System

LEVEL I
Randomized, controlled clinical trials - This is the most objective and valid study results.  This study has posted the highest level of quality for evidence based medicine.

LEVEL II
Prospective non-randomized, comparative studies - This is the second most objective and valid study results.

LEVEL III
Retrospective comparative or case controlled studies - These studies look back historically and compare them with other cases in the past. The problem with this system is that these past patients may not have been chosen or treated - or not treated at all - on equal standings.

LEVEL IV
Case Series - This where a group of patients have a particular treatment, and then observations are made about them. This does not differentiate between the success or failure of the treatment compared to other treatments or no treatment at all. For example treating back pain for 10 days by drinking pomegranate juice may show all patients got better and conclude this should be the treatment for back pain. However, usually all back pain gets better in 10 days no matter what one does.

LEVEL V
Expert opinion. This is a person's opinion only. It's an editorial, and is considered the lowest level of evidence to support a position. AME considers this to be Comparable to hearsay.

For More Information
On Evidence Based Medicine
Rating System Click Here