	Are pharmaceutical company Phase III clinical trials becoming more complex?  The most broadly based database available, ClinicalTrials.gov, does not support the assertion that clinical trials have become more complex in study/protocol design or execution. Illustrative is the number of countries used in pharmaceutical company sponsored Phase III clinical trials. 

	The number of countries used in commercially sponsored Phase III clinical trials has not changed in recent years. It is essential to stratify the results or otherwise the data appear to show that the number of countries per study has actually declined, so we stratified the studies by planned study duration: less than one year, 1 to 2 years and 3 or more years. This is important because the longer the planned study, the more likely the study may be opening sites in additional countries. When stratified this way, the data show practically no change over the years covered.

Average Number of Countries per Study by Designed Study Duration by Year

Source: Department of Health Policy and Public Policy, University of the Sciences, Philadelphia, PA, using ClinicalTrials.gov data.

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The number of countries used in commercially sponsored Phase III clinical trials has not changed in recent years.