Editing Randomized controlled trial (section)

=== Relative importance and observational studies ===
Two studies published in ''[[The New England Journal of Medicine]]'' in 2000 found that [[Observational study|observational studies]] and RCTs overall produced similar results.<ref name="Benson-2000">{{Cite journal |vauthors=Benson K, Hartz AJ |date=June 2000 |title=A comparison of observational studies and randomized, controlled trials |journal=The New England Journal of Medicine |volume=342 |issue=25 |pages=1878–1886 |doi=10.1056/NEJM200006223422506 |pmid=10861324 |doi-access=free}}</ref><ref name="Concato-2000">{{Cite journal |vauthors=Concato J, Shah N, Horwitz RI |date=June 2000 |title=Randomized, controlled trials, observational studies, and the hierarchy of research designs |journal=The New England Journal of Medicine |volume=342 |issue=25 |pages=1887–1892 |doi=10.1056/NEJM200006223422507 |pmc=1557642 |pmid=10861325}}</ref> The authors of the 2000 findings questioned the belief that "observational studies should not be used for defining evidence-based medical care" and that RCTs' results are "evidence of the highest grade."<ref name="Benson-2000" /><ref name="Concato-2000" /> However, a 2001 study published in ''[[Journal of the American Medical Association]]'' concluded that "discrepancies beyond chance do occur and differences in estimated magnitude of treatment effect are very common" between observational studies and RCTs.<ref name="Ioannidis-2001">{{Cite journal |vauthors=Ioannidis JP, Haidich AB, Pappa M, Pantazis N, Kokori SI, Tektonidou MG, Contopoulos-Ioannidis DG, Lau J |date=August 2001 |title=Comparison of evidence of treatment effects in randomized and nonrandomized studies |journal=JAMA |volume=286 |issue=7 |pages=821–830 |citeseerx=10.1.1.590.2854 |doi=10.1001/jama.286.7.821 |pmid=11497536}}</ref> According to a 2014 (updated in 2024) Cochrane review, there is little evidence for significant effect differences between observational studies and randomized controlled trials.<ref name=":0">{{Cite journal |last1=Toews |first1=Ingrid |last2=Anglemyer |first2=Andrew |last3=Nyirenda |first3=John Lz |last4=Alsaid |first4=Dima |last5=Balduzzi |first5=Sara |last6=Grummich |first6=Kathrin |last7=Schwingshackl |first7=Lukas |last8=Bero |first8=Lisa |date=2024-01-04 |title=Healthcare outcomes assessed with observational study designs compared with those assessed in randomized trials: a meta-epidemiological study |journal=The Cochrane Database of Systematic Reviews |volume=1 |issue=1 |pages=MR000034 |doi=10.1002/14651858.MR000034.pub3 |issn=1469-493X |pmc=10765475 |pmid=38174786 }}</ref>  To evaluate differences it is necessary to consider things other than design, such as heterogeneity, population, intervention or comparator.<ref name=":0" />

Two other lines of reasoning question RCTs' contribution to scientific knowledge beyond other types of studies:
* If study designs are ranked by their potential for new discoveries, then [[Anecdotal evidence#Scientific context|anecdotal evidence]]{{Broken anchor|date=2024-06-29|bot=User:Cewbot/log/20201008/configuration|target_link=Anecdotal evidence#Scientific context|reason= The anchor (Scientific context) [[Special:Diff/1231587843|has been deleted]].}} would be at the top of the list, followed by observational studies, followed by RCTs.<ref name="Vandenbroucke-2008">{{Cite journal |vauthors=Vandenbroucke JP |date=March 2008 |title=Observational research, randomised trials, and two views of medical science |journal=PLOS Medicine |volume=5 |issue=3 |pages=e67 |doi=10.1371/journal.pmed.0050067 |pmc=2265762 |pmid=18336067 |doi-access=free}}</ref>
* RCTs may be unnecessary for treatments that have dramatic and rapid effects relative to the expected stable or progressively worse natural course of the condition treated.<ref name="Black-1996" /><ref name="Glasziou-2007">{{Cite journal |vauthors=Glasziou P, Chalmers I, Rawlins M, McCulloch P |date=February 2007 |title=When are randomised trials unnecessary? Picking signal from noise |journal=BMJ |volume=334 |issue=7589 |pages=349–351 |doi=10.1136/bmj.39070.527986.68 |pmc=1800999 |pmid=17303884}}</ref> One example is [[History of cancer chemotherapy#Combination chemotherapy|combination chemotherapy]] including [[cisplatin]] for [[Metastasis|metastatic]] [[testicular cancer]], which increased the cure rate from 5% to 60% in a 1977 non-randomized study.<ref name="Glasziou-2007" /><ref name="Einhorn-2002">{{Cite journal |author-link=Lawrence Einhorn |vauthors=Einhorn LH |date=April 2002 |title=Curing metastatic testicular cancer |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=99 |issue=7 |pages=4592–4595 |doi=10.1073/pnas.072067999 |pmc=123692 |pmid=11904381 |doi-access=free}}</ref>