Rationale for multi-centre trials

As indicated in the ICH E9 guideline there are two reasons why we conduct multicentre trials  

To recruit sufficient numbers of patients within an appropriate timeframe 

To allow the evaluation of the homogeneity of the treatment effect and provide a basis for generalisability 

The first issue is of practical importance there is probably no other way the required numbers of patients could be recruited. The second issue has more of a statistical basis. A multi-centre structure enables us to look at treatment differences in different centres or clusters of centres to assess whether what we are seeing is a consistent effect. Without this consistency it would be very difficult to draw conclusions about the value of the treatment across a broad patient population. 

Statistical Thinking for Non-Statisticians in Drug Regulation Richard Kay 2007 John Wiley Sons, Ltd ISBN 978-0-470-31971-0 

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