BMJ 2001;322:879-880 ( 14 April )

Editorials

Any casualties in the clash of randomised and observational evidence?

Norecent comparisons have studied selected questions, but we do need more data

The first 150 words of the full text of this article appear below.

Randomised controlled trials and observational studies are often seen as mutually exclusive, if not opposing, methods of clinical research. Two recent reports, however, identified clinical questions (19 in one report,¹ five in the other²) where both randomised trials and observational methods had been used to evaluate the same question, and performed a head to head comparison of them. In contrast to the belief that randomised controlled trials are more reliable estimators of how much a treatment works, both reports found that observational studies did not overestimate the size of the treatment effect compared with their randomised counterparts. The authors say that the merits of well designed observational studies may need to be re-evaluated: case-control and cohort studies may need to assume more respect in assessing medical therapies and largescale observational databases should be better exploited. ^{1 2} The first claim flies in the face of half a century of thinking, so are . . . [Full text of this article]

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Rapid Responses:

Read all Rapid Responses

Random variability or bias?

Chris Gale
bmj.com, 18 Apr 2001 [Full text]

Re: Random variability or bias?

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bmj.com, 23 Apr 2001 [Full text]

Randomized and observational evidence: time for a change in the paradigm?

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bmj.com, 26 Apr 2001 [Full text]

Not All Clinical Trials Are Created Equal

Vance W Berger
bmj.com, 28 Apr 2001 [Full text]

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