Biases in articles about biases
Our work about bias in pharmacoeconomic studies (1) is included in
the review by Lexchin et al (2). In the study, we found that 22 (92%) of
the 24 studies published in a specialized journal reported positive
results, 83% of them being sponsored by the pharmaceutical industry; while
only 34 (49%) of the 69 studies published in general medical journals, 74%
of them being financed by government agencies, reported favorable results
for the new intervention tested (1).
Our results suggested that bias in economic analyses could operate in
different directions. Governments and payers have a legitimate interest in
reducing their health expenditure budget, and this might be considered a
source of potential bias to show that the cheapest drug is the most cost-
effective, particularly so when these institutions are financing the
medicines. In such cases, an "unfavorable" result could result in the
withdrawal of finance for the new technology with the subsequent financial
saving. In our work, we stated that, in pharmacoeconomic evaluations it
would be necessary to reconsider the meaning of the term "positive result"
so as to indicate the result which coincides with the sponsor's
expectations (in opposition to the classical definition of the term: the
results which shows a difference in favor of the new therapy).
Surprisingly, the main results of our paper (relative low number of
positive results in pharmacoeconomic articles funded by “independent
sources”) are not discussed at all in the paper by Lexchin et al (although
they are presented in Figure 2), probably because these results are not
consistent with the commonly accepted opinion. We think that this partial
presentation of the results represent a bias. In their article, Lexchin et
al assert that “authors and editors should consider including a statement
concerning prior beliefs of the investigators about the uncertainty of the
treatments that are reported” . We endorse this proposal, and we would
recommend that a similar statement is included in articles that analyze
bias, but in this case, the statement should be on the prior beliefs of
the investigators about the direction of the bias.
This is not the first time that we perceive this kind of bias in
paper about bias. One of the papers also mentioned in the review (3)
stated that pharmaceutical company-sponsored studies were more likely than
non-profit-sponsored studies to overstate quantitative results, i.e., a
favorable qualitative conclusion when quantitative results were neutral or
unfavorable”. Paradoxically, the authors based the affirmation in results
that were not statistically significant.
Probably, the authors of the review will argue that the objective of
the study was to analyze biases of studies founded by pharmaceutical
companies and not about biases of studies funded by “non-profit”
organizations. They are right, but the systematic tendency to analyze the
problem of industry-funded research and not the problems of other kind of
research may be considered also a kind of bias.
We think that measures should be taken to minimize biases in clinical
research. The pharmaceutical industry has already started to work on that.
The recent policies encouraging publication of negative results by PhRMA
(4) are good examples. Hopefully these policies have a double effect: to
decrease publication bias in studies sponsored by the industry and to
start to analyze the problem of bias from a wider perspective.
1. Sacristán JA, Bolaños E, Hernandez JM, Soto J, Galende I.
Publication bias in health economic studies. Pharmacoeconomics 1997; 11:
2. Lexchin J, Bero LA, Djulbegovic B, Clark O. Pharmaceutical industry
sponsorship and research outcome and quality: systematic review. BMJ 2003;
3. Friedberg M, Saffran B, Stinson TJ, Nelson W, Bennet CL. Evaluation of
conflict of interest in economic analyses of new drugs used in oncology.
JAMA 1999; 282: 1453-7.
4. PhRMA Principles on Conduct of Clinical Trials and Communication of
Clinical Trial Results, 2002
Jose A Sacristan and Jesus M Hernandez are employees of Eli Lilly & Co
Competing interests: No competing interests