Conflict of interest.
You should always be cautious about industry sponsored research, but not so cautious as to be cynical. There is solid data to show that outcomes of reviews of passive smoking were influenced by affiliation with the tobacco industry (Barnes 1998). Similarly, in studies of calcium channel antagonists, safety claims were influenced by financial relationships with pharmaceutical manufacturers (Stelfox 1998). You should be especially cautious about symposia sponsored by a single pharmaceutical company, as these are more likely to have misleading titles and to bypass the peer review process (Bero 1992).
Resources
A Frank Statement to Cigarette Smokers. Tobacco Industry Research Committee. Accessed on 2003-06-18. "Recent reports on experiments with mice have given wide publicity to a theory that cigarette smoking is in some way linked with lung cancer in human beings." www.pmdocs.com/getimg.asp?pgno=0&start=0&bool=Frank%20Statement&docid=2015002376
Why review articles on the health effects of passive smoking reach different conclusions. D. E. Barnes, L. A. Bero. Jama 1998: 279(19); 1566-70. OBJECTIVE: To determine whether the conclusions of review articles on the health effects of passive smoking are associated with article quality, the affiliations of their authors, or other article characteristics. DATA SOURCES: Review articles published from 1980 to 1995 were identified through electronic searches of MEDLINE and EMBASE and from a database of symposium proceedings on passive smoking. ARTICLE SELECTION: An article was included if its stated or implied purpose was to review the scientific evidence that passive smoking is associated with 1 or more health outcomes. Articles were excluded if they did not focus specifically on the health effects of passive smoking or if they were not written in English. DATA EXTRACTION: Review article quality was evaluated by 2 independent assessors who were trained, followed a written protocol, had no disclosed conflicts of interest, and were blinded to all study hypotheses and identifying characteristics of articles. Article conclusions were categorized by the 2 assessors and by one of the authors. Author affiliation was classified as either tobacco industry affiliated or not, based on whether the authors were known to have received funding from or participated in activities sponsored by the tobacco industry. Other article characteristics were classified by one of the authors using predefined criteria. DATA SYNTHESIS: A total of 106 reviews were identified. Overall, 37% (39/106) of reviews concluded that passive smoking is not harmful to health; 74% (29/39) of these were written by authors with tobacco industry affiliations. In multiple logistic regression analyses controlling for article quality, peer review status, article topic, and year of publication, the only factor associated with concluding that passive smoking is not harmful was whether an author was affiliated with the tobacco industry (odds ratio, 88.4; 95% confidence interval, 16.4-476.5; P<.001). CONCLUSIONS: The conclusions of review articles are strongly associated with the affiliations of their authors. Authors of review articles should disclose potential financial conflicts of interest, and readers of review articles should consider authors' affiliations when deciding how to judge an article's conclusions. [Medline]
Conflict of interest and the American Journal of Bioethics. K. A. Carroll, G. McGee. American Journal of Bioethics 2002: 2(3); 1-2. [Medline]
Unconventional cancer therapies: What we need is rigorous research, not closed minds. E. Ernst. Chest 2000: 117(2); 307-8. [Full text] [PDF]
Reference bias in reports of drug trials. P. C. Gotzsche. Br Med J (Clin Res Ed) 1987: 295(6599); 654-6. Articles published before 1985 describing double blind trials of two or more non-steroidal anti-inflammatory drugs in rheumatoid arthritis were examined to see whether there was any bias in the references they cited. Althogether 244 articles meeting the criteria were found through a Medline search and through examining the reference lists of the articles retrieved. The drugs compared in the studies were classified as new or as control drugs and the outcome of the trial as positive or not positive. The reference lists of all papers with references to other trials on the new drug were then examined for reference bias. Positive bias was judged to have occurred if the reference list contained a higher proportion of references with a positive outcome for that drug than among all the articles assumed to have been available to the authors (those published more than two years earlier than the index article). Altogether 133 of the 244 articles were excluded for various reasons--for example, 44 because of multiple publication and 19 because they had no references. Among the 111 articles analysed bias was not possible in the references of 35 (because all the references gave the same outcome); 10 had a neutral selection of references, 22 a negative selection, and 44 a positive selection--a significant positive bias. This bias was not caused by better scientific standing of the cited articles over the uncited ones. Thus retrieving literature by scanning reference lists may produce a biased sample of articles, and reference bias may also render the conclusions of an article less reliable.
Bias in analytic research. D. L. Sackett. J Chronic Dis 1979: 32(1-2); 51-63. Abstract not available.
Declaring financial competing interests: survey of five general medical journals. A. Hussain, R. Smith. British Medical Journal 2001: 323(7307); p263-4. Abstract not available. [Medline] [Full text] [PDF]
Association between competing interests and authors' conclusions: epidemiological study of randomised clinical trials published in the BMJ. L. L. Kjaergard, B. Als-Nielsen. British Medical Journal 2002: 325(7358); 249. Objective: To assess the association between competing interests and authors' conclusions in randomised clinical trials. Design: Epidemiological study of randomised clinical trials published in the BMJ from January 1997 to June 2001. Financial competing interests were defined as funding by for profit organisations and other competing interests as personal, academic, or political. Studies: 159 trials from 12 medical specialties. Main outcome measures: Authors' conclusions defined as interpretation of extent to which overall results favoured experimental intervention. Conclusions appraised on 6 point scale; higher scores favour experimental intervention. Results: Authors' conclusions were significantly more positive towards the experimental intervention in trials funded by for profit organisations alone compared with trials without competing interests (mean difference 0.48 (SE 0.13), P=0.014), trials funded by both for profit and non-profit organisations (0.30 (SE 0.10), P=0.003), and trials with other competing interests (0.45 (SE 0.13), P=0.006). Other competing interests and funding from both for profit and non-profit organisations were not significantly associated with authors' conclusions. The association between financial competing interests and authors' conclusions was not explained by methodological quality, statistical power, type of experimental intervention (pharmacological or non-pharmacological), type of control intervention (for example, placebo or active drug), or medical specialty. Conclusions: Authors' conclusions in randomised clinical trials significantly favoured experimental interventions if financial competing interests were declared. Other competing interests were not significantly associated with authors' conclusions.
When statistics provide unsatisfying answers: revisiting the breast self-examination controversy. B. H. Lerner. Cmaj 2002: 166(2); 199-201.
Nonfinancial conflicts of interest in research. N. G. Levinsky. N Engl J Med 2002: 347(10); 759-61. Abstract not available yet. [Medline] [Abstract]
Academic freedom in clinical research. D. G. Nathan, D. J. Weatherall. New England Journal of Medicine 2002: 347(17); 1368-71. [Medline] [Abstract]
Cholesterol lowering trials in coronary heart disease: frequency of citation and outcome. U. Ravnskov. British Journal of Medicine 1992: 305(6844); 15-19. ABSTRACT: OBJECTIVE--To see if the claim that lowering cholesterol values prevents coronary heart disease is true or if it is based on citation of supportive trials only. DESIGN--Comparison of frequency of citation with outcome of all controlled cholesterol lowering trials using coronary heart disease or death, or both, as end point. SUBJECTS--22 controlled cholesterol lowering trials. RESULTS--Trials considered by their directors as supportive of the contention were cited almost six times more often than others, according to Science Citation Index. Apart from trials discontinued because of alleged side effects of treatment, unsupportive trials were not cited after 1970, although their number almost equalled the number considered supportive. In three supportive reviews the outcome of the selected trials was more favourable than the outcome of the excluded and ignored trials. In the 22 controlled cholesterol lowering trials studied total and coronary heart disease mortality was not changed significantly either overall or in any subgroup. A statistically significant 0.32% reduction in non-fatal coronary heart disease seemed to be due to bias as event frequencies were unrelated to trial length and to mean net reduction in cholesterol value; individual changes in cholesterol values were unsystematically or not related to outcome; and after correction for a small but significant increase in non-medical deaths in the intervention groups total mortality remained unchanged (odds ratio 1.02). CONCLUSIONS--Lowering serum cholesterol concentrations does not reduce mortality and is unlikely to prevent coronary heart disease. Claims of the opposite are based on preferential citation of supportive trials.
Beyond conflict of interest. Transparency is the key [editorial]. R. Smith. Bmj 1998: 317(7154); 291-2. [Full text] [PDF]
Conflict of interest in the debate over calcium-channel antagonists. H. T. Stelfox, G. Chua, O. Rourke K, A. S. Detsky. N Engl J Med 1998: 338(2); 101-6. BACKGROUND: Physicians' financial relationships with the pharmaceutical industry are controversial because such relationships may pose a conflict of interest. It is unknown to what extent industry support of medical education and research influences the opinions and behavior of clinicians and researchers. The recent debate over the safety of calcium-channel antagonists provided an opportunity to examine the effect of financial conflicts of interest. METHODS: We searched the English-language medical literature published from March 1995 through September 1996 for articles examining the controversy about the safety of calcium-channel antagonists. Articles were reviewed and classified as being supportive, neutral, or critical with respect to the use of calcium-channel antagonists. The authors of the articles were asked about their financial relationships with both manufacturers of calcium-channel antagonists and manufacturers of competing products (i.e., beta-blockers, angiotensin-converting-enzyme inhibitors, diuretics, and nitrates). We examined the authors' published positions on the safety of calcium-channel antagonists according to their financial relationships with pharmaceutical companies. RESULTS: Authors who supported the use of calcium-channel antagonists were significantly more likely than neutral or critical authors to have financial relationships with manufacturers of calcium-channel antagonists (96 percent, vs. 60 percent and 37 percent, respectively; P<0.001). Supportive authors were also more likely than neutral or critical authors to have financial relationships with any pharmaceutical manufacturer, irrespective of the product (100 percent, vs. 67 percent and 43 percent, respectively; P< 0.001). CONCLUSIONS: Our results demonstrate a strong association between authors' published positions on the safety of calcium-channel antagonists and their financial relationships with pharmaceutical manufacturers. The medical profession needs to develop a more effective policy on conflict of interest. We support complete disclosure of relationships with pharmaceutical manufacturers for clinicians and researchers who write articles examining pharmaceutical products.
This webpage was written by Steve Simon on (unknown date), edited by Steve Simon, and was last modified on 2008-07-08. This page needs minor revisions. Category: Statistical evidence