This figure below, published in
- Erythropoietin, uncertainty principle and cancer related anaemia. Clark O, Adams JR, Bennett CL, Djulbegovic B. BMC Cancer 2002: 2(1); 23. [Medline]](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12270068&dopt=Abstract) [Abstract]](http://www.biomedcentral.com/1471-2407/2/23/abstract) [Full text]](http://www.biomedcentral.com/1471-2407/2/23) [PDF]](http://www.biomedcentral.com/content/pdf/1471-2407-2-23.pdf)
shows cumulative meta-analysis, which is the cumulated effects over time of studies in the use of erythropoietin (EPO) to treat cancer related anemia. The outcome variable, the odds ratio for whether a patient requires transfusion, showed a significant benefit for EPO and that sufficient evidence had already accumulated by 1995. If such a meta-analysis had been performed back then, there would have been no need to run the additional trials. These redundant trials are bad because they wasted scarce research dollars on a topic where sufficient information had already been accumulated to answer the research question. They are also bad because half of the patients in these post-1995 trials received no treatment or placebo, even though there was enough evidence at that time to show that this is an inferior option.
There has been a suggestion that any protocol submitted to an Institutional Review Board (IRB) should include a systematic overview or meta-analysis of the previous research (see Chalmers 1996), rather than just a simple literature review, to prevent future IRBs from making the same mistake of those that approved the post-1995 studies of EPO. In some situations, that is definitely overkill, but it is a suggestion worth serious consideration in other circumstances.
Since BMC Cancer is published with an open access license, I can freely reproduce this image without getting permission, as long as I cite the source. I try to preferentially cite such resources because they make it easy to include their content on my web pages and in my teaching.
- Changes in clinical trials mandated by the advent of meta-analysis. Chalmers TC, Lau J. Stat Med 1996: 15(12); 1263-8; discussion 1269-72. [Medline]](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8817800&dopt=Abstract)
You can find an earlier version of this page on my original website.