Sponsored Clinical Trials and Bias

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Sir: I read with great interest your editorial¹ and the 2 letters from the February 2007 issue of your journal^2,3 highlighting the important concern about the source of funding influence on the outcome of interest.

In addition to the recent review by Heres et al.⁴ that you refer to in your editorial,¹ the relationship between funding source and study outcome, which is so beautifully illustrated by the exchange between your 2 correspondents,^2,3 was investigated in several other published studies.^5-15 With one exception,¹¹ these studies showed that industry support was uniformly associated with positive study outcome for the sponsored intervention either as a trend⁸ or, most times, at significant levels.^{5,6,9,10,12-15}' ‹