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Association between competing interests and authors' conclusions: epidemiological study of randomised clinical trials published in the BMJ

BMJ 2002; 325 doi: https://doi.org/10.1136/bmj.325.7358.249 (Published 03 August 2002) Cite this as: BMJ 2002;325:249

Funding-related bias in clinical trials

Dear Editor,

Kjaergard & Als-Nielsen's study findings (1) confirm our earlier
study (2). We conducted a study looking for bias in randomised clinical
trials published in peer-reviewed journals, and funded by a drug company
when comparing its product with that of a direct competitor. Our model was
that of inhaled corticosteroids with similar efficacy, where two
pharaceutical companies dominate the market, thereby allowing direct
comparison. We found that in the majority of cases, the conclusion of the
abstract favoured the product of the sponsor, which was statistically
highly significant. Thus, of the two sponsors' trials, 72% and 78% of
trials favoured their own product, which is very unlikely to occur by
chance.

The BMJ has taken the laudable step of publishing Kjaergard &
Als-Nielsen's study as a full paper, thus allowing constructive debate on
this important issue. It is clear that comparative clinial studies should
be independent from the sponsors, e.g. supervised by an independent body
such as NICE, otherwise this problem will continue to occur.

Yours faithfully,

Paul Thomas,

Ken-Soon Tan,

Deborah Yates.

Kjaergard LL, Als-Nielsen B. Association between competing interests
and authors' conclusions: epidemiological study of randomised clinical
trials published in the BMJ. 2002; 325: 249.

2. Thomas PS, Tan K-S, Yates DH. Sponsorship, aothorship and
accountability. Lancet 2002; 359: 351 (letter).

Authors funded by: NHMRC Australia, Dust Diseases Board of NSW.

Competing interests: No competing interests

22 August 2002
Paul S THOMAS
Senior Lecturer
Ken-Soon Tan, and Deborah Yates
UNSW, Randwick, Sydney NSW 2031, Australia