The outcomes of clinical trials funded by pharmaceutical companies, or whose authors have financial conflicts of interest, “far more frequently” favour the sponsoring company’s products than when the study funding comes from other sources, a systematic review by German researchers has concluded.

Also, the interpretation of data in the conclusions of industry-funded trials more often flatters the sponsor, says the team headed by Professor Wolf-Dieter Ludwig, chairman of the Drug Commission at the German Medical Association.

The principle of equipoise (uncertainty as to which of alternative treatment approaches benefits the patient most), which forms the ethical foundation of clinical studies where patients are assigned to different treatment arms, “seems to be violated in many studies funded by pharmaceutical companies”, Ludwig et al comment in their paper published in the latest issue of Deutsches Ärzteblatt International.

The review looked at 57 articles published between 1 November 2002 and 16 December 2009 that provided empirical data on how pharmaceutical company funding affected various aspects of clinical trials (e.g., protocol, conduct, results, conclusions, publication). A descriptive approach was used, in an effort “to ensure comprehensive portrayal of the various ways in which influence could be exerted”, the authors explain. No hypotheses were advanced or statistical analyses performed.

Of the 57 publications included in the review, 26 sought to ascertain whether the results and/or conclusions of clinical trials depended on the type of funding provided or on authors’ financial conflicts of interest. In 23 cases, these studies “came to the conclusion that there was a positive correlation between the financing of a study by pharmaceutical companies and/or conflicts of interest on the part of the authors and results or conclusions that were favourable to the sponsor”, Ludwig et al note.

In four of the studies, it was “apparent that the findings were interpreted favourably towards the pharmaceutical concern that had funded the study, independent of the results”, they add. In three more investigations, no clear association was identified between pharmaceutical company funding and results favouring the sponsors. However, in one of these articles only 24 publications were analysed and the author disclosed Speakers’ Bureau – Pfizer’ as a conflict of interest, the researchers point out.

Protocol design

Five of the 57 articles looked at whether industry funding affected study protocol design. The use of placebos was found to be significantly more common in randomised controlled trials (RCT) of drugs for psoriasis that were company-backed than in those with funding from other sources.

And several studies of treatment for premature ejaculation that were sponsored by a pharmaceutical company proved “to have disregarded the relevant objective endpoint”, Ludwig et al say. One other article revealed a RCT for rofecoxib (Vioxx) to have been a ‘seeding’ or marketing trial, along with indications of other irregularities.

Four of the 57 publications included in the review concerned themselves with the methodological quality of drug trials in relation to financial support.

In two of these investigations, Ludwig et al report, the methodological quality of industry-backed clinical trials was found to be comparable to, or even better than, trials where the sponsors had no commercial interest. In only one investigation did this quality tend to be inferior in the industry-funded studies.