Publication bias: Difference between revisions

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Publication bias is defined as "the influence of study results on the chances of publication and the tendency of investigators, reviewers, and editors to submit or accept manuscripts for publication based on the direction or strength of the study findings. Publication bias has an impact on the interpretation of clinical trials and meta-analyses. Bias can be minimized by insistence by editors on high-quality research, thorough literature reviews, acknowledgement of conflicts of interest, modification of peer review practices, etc."<ref name="title">{{cite web |url=http://www.nlm.nih.gov/cgi/mesh/2007/MB_cgi?term=publication+bias |title=Publication bias |accessdate=2007-12-17 |author=National Library of Medicine |authorlink= |coauthors= |date= |format= |work= |publisher= |pages= |language= |archiveurl= |archivedate= |quote=}}</ref> Publication bias has been documented to occur<ref name="pmid1727960">{{cite journal |author=Dickersin K, Min YI, Meinert CL |title=Factors influencing publication of research results. Follow-up of applications submitted to two institutional review boards |journal=JAMA |volume=267 |issue=3 |pages=374–8 |year=1992 |pmid=1727960 |doi=}}</ref>.
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Publication bias may be due to authors not submitting negative studies for publication.<ref name="pmid12876092">{{cite journal |author=Krzyzanowska MK, Pintilie M, Tannock IF |title=Factors associated with failure to publish large randomized trials presented at an oncology meeting |journal=JAMA |volume=290 |issue=4 |pages=495–501 |year=2003 |pmid=12876092 |doi=10.1001/jama.290.4.495}}</ref> This may especially be true of studies authored by industries with conflicts of interest.<ref name="pmid12775615">{{cite journal |author=Melander H, Ahlqvist-Rastad J, Meijer G, Beermann B |title=Evidence b(i)ased medicine--selective reporting from studies sponsored by pharmaceutical industry: review of studies in new drug applications |journal=BMJ |volume=326 |issue=7400 |pages=1171–3 |year=2003 |pmid=12775615 |doi=10.1136/bmj.326.7400.1171}}</ref>
In [[academic journal]]s and [[scientific journal]]s, '''publication bias''' is defined as "the influence of study results on the chances of publication and the tendency of investigators, reviewers, and editors to submit or accept manuscripts for publication based on the direction or strength of the study findings. Publication bias has an impact on the interpretation of [[randomized controlled trial|clinical trials]] and [[meta-analysis|meta-analyses]]. Bias can be minimized by insistence by editors on high-quality research, thorough literature reviews, acknowledgment of conflicts of interest, modification of peer review practices, etc."<ref>{{MeSH}}</ref>


An example of probable publication bias is in the studies of [[glucosamine]] and [[chondroitin]] for treatment of [[osteoarthritis]]. In an initial meta-analysis, the authors noted evidence of publication bias during examination of the results.<ref name="pmid10732937">{{cite journal |author=McAlindon TE, LaValley MP, Gulin JP, Felson DT |title=Glucosamine and chondroitin for treatment of osteoarthritis: a systematic quality assessment and meta-analysis |journal=JAMA |volume=283 |issue=11 |pages=1469–75 |year=2000 |pmid=10732937 |doi=|url=http://jama.ama-assn.org/cgi/content/full/283/11/1469}}</ref> A subsequent large [[randomized controlled trial]]<ref name="pmid16495392">{{cite journal |author=Clegg DO, Reda DJ, Harris CL, ''et al'' |title=Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis |journal=N. Engl. J. Med. |volume=354 |issue=8 |pages=795–808 |year=2006 |pmid=16495392 |doi=10.1056/NEJMoa052771}}</ref> and meta-analyses including the large trial were negative<ref name="pmid17599746">{{cite journal |author=Vlad SC, LaValley MP, McAlindon TE, Felson DT |title=Glucosamine for pain in osteoarthritis: why do trial results differ? |journal=Arthritis Rheum. |volume=56 |issue=7 |pages=2267–77 |year=2007 |pmid=17599746 |doi=10.1002/art.22728}}</ref><ref name="pmid17438317">{{cite journal |author=Reichenbach S, Sterchi R, Scherer M, ''et al'' |title=Meta-analysis: chondroitin for osteoarthritis of the knee or hip |journal=Ann. Intern. Med. |volume=146 |issue=8 |pages=580–90 |year=2007 |pmid=17438317 |doi=|url=http://www.annals.org/cgi/content/full/146/8/580}}</ref>.
Publication bias has been documented to occur.<ref name="pmid1727960">{{cite journal |author=Dickersin K, Min YI, Meinert CL |title=Factors influencing publication of research results. Follow-up of applications submitted to two institutional review boards |journal=JAMA |volume=267 |issue=3 |pages=374–8 |year=1992 |pmid=1727960 |doi=}}</ref>


==Meta-analysis==
The small study effect is closely related. The small study effect is the observation that small studies tend to report more positive results.<ref name="pmid20639294">{{cite journal|  author=Nüesch E, Trelle S, Reichenbach S, Rutjes AW, Tschannen B,  Altman DG et al.| title=Small study effects in meta-analyses of  osteoarthritis trials: meta-epidemiological study. | journal=BMJ | year=  2010 | volume= 341 | issue=  | pages= c3515 | pmid=20639294 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20639294  | pmc=PMC2905513 | doi=10.1136/bmj.c3515 }} </ref><ref name="pmid11451790">{{cite journal|  author=Sterne JA, Egger M, Smith GD| title=Systematic reviews in health  care: Investigating and dealing with publication and other biases in  meta-analysis. | journal=BMJ | year= 2001 | volume= 323 | issue= 7304 |  pages= 101-5 | pmid=11451790 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=clinical.uthscsa.edu/cite&retmode=ref&cmd=prlinks&id=11451790  | pmc=PMC1120714 }} </ref> This is especially a threat when the original studies in a meta-analysis are less than 50 patients in size.<ref>F. Richy, O. Ethgen, O. Bruyere, F. Deceulaer & J. Reginster : [http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ije/vol1n2/sse.xml  From Sample Size to Effect-Size: Small Study Effect Investigation  (SSEi)] .  The Internet Journal of Epidemiology.  2004 Volume 1 Number 2</ref>
Publication bias is a major threat to the validity of [[meta-analysis]]. Publication bias against negative studies may threaten the validity of [[meta-analysis|meta-analyses]] that are positive and all the studies included within the meta-analysis are small.<ref name="pmid10845965">{{cite journal |author=Sutton AJ, Duval SJ, Tweedie RL, Abrams KR, Jones DR |title=Empirical assessment of effect of publication bias on meta-analyses |journal=BMJ |volume=320 |issue=7249 |pages=1574–7 |year=2000 |pmid=10845965 |doi=}}</ref><ref name="pmid9310563">{{cite journal |author=Egger M, Davey Smith G, Schneider M, Minder C |title=Bias in meta-analysis detected by a simple, graphical test |journal=BMJ |volume=315 |issue=7109 |pages=629–34 |year=1997 |pmid=9310563 |doi=}}</ref>
 
==Examples==
An example of probable publication bias is in the studies of [[glucosamine]] and [[chondroitin]] for treatment of [[osteoarthritis]]. In an initial [[meta-analysis]], the authors noted evidence of publication bias during examination of the results.<ref name="pmid10732937">{{cite journal |author=McAlindon TE, LaValley MP, Gulin JP, Felson DT |title=Glucosamine and chondroitin for treatment of osteoarthritis: a systematic quality assessment and meta-analysis |journal=JAMA |volume=283 |issue=11 |pages=1469–75 |year=2000 |pmid=10732937 |doi=|url=http://jama.ama-assn.org/cgi/content/full/283/11/1469
}}</ref>
 
A subsequent large [[randomized controlled trial]]<ref name="pmid16495392">{{cite journal |author=Clegg DO, Reda DJ, Harris CL, ''et al'' |title=Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis |journal=N. Engl. J. Med. |volume=354 |issue=8 |pages=795–808 |year=2006 |pmid=16495392 |doi=10.1056/NEJMoa052771
}}</ref> and [[meta-analysis|meta-analyses]] including the large trial were negative.<ref name="pmid17599746">{{cite journal |author=Vlad SC, LaValley MP, McAlindon TE, Felson DT |title=Glucosamine for pain in osteoarthritis: why do trial results differ? |journal=Arthritis Rheum. |volume=56 |issue=7 |pages=2267–77 |year=2007 |pmid=17599746 |doi=10.1002/art.22728}}</ref><ref name="pmid17438317">{{cite journal |author=Reichenbach S, Sterchi R, Scherer M, ''et al'' |title=Meta-analysis: chondroitin for osteoarthritis of the knee or hip |journal=Ann. Intern. Med. |volume=146 |issue=8 |pages=580–90 |year=2007 |pmid=17438317 |doi=|url=http://www.annals.org/cgi/content/full/146/8/580
}}</ref>
 
Another example is the selective publication of [[randomized controlled trial]]s of [[antidepressant]]s<ref name="pmid18199864">{{cite journal |author=Turner EH, Matthews AM, Linardatos E, Tell RA, Rosenthal R |title=Selective publication of antidepressant trials and its influence on apparent efficacy |journal=N. Engl. J. Med. |volume=358 |issue=3 |pages=252–60 |year=2008 |pmid=18199864 |doi=10.1056/NEJMsa065779}}</ref> or of positive trials in general<ref name="pmid20679560">{{cite journal| author=Bourgeois FT, Murthy S, Mandl KD| title=Outcome reporting among drug trials registered in ClinicalTrials.gov. | journal=Ann Intern Med | year= 2010 | volume= 153 | issue= 3 | pages= 158-66 | pmid=20679560 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20679560 | doi=10.1059/0003-4819-153-3-201008030-00006 }} </ref>.
 
Anecdotal examples include partial publication of results of trails of the [[antiviral agent]] [[oseltamivir]] for the prevention of [[influenza]].<ref>Jefferson T et al. [http://www.bmj.com/content/342/bmj.c7258 Ensuring safe and effective drugs: who can do what it takes]?. BMJ 2011; 342:c7258 {{doi| 10.1136/bmj.c7258}}</ref>
 
==Frequency of occurrence==
===Randomized controlled trials===
Publication bias, or bias in interpretation of studies, may occur in 25%<ref>{{Cite journal | doi = 10.1371/journal.pmed.1001189 | volume = 9
| issue = 3 | pages = e1001189 | last = Turner | first = Erick H. | coauthors = Daniel Knoepflmacher, Lee Shapley | title = Publication Bias in Antipsychotic Trials: An Analysis of Efficacy Comparing the Published Literature to the US Food and Drug Administration Database | journal = PLoS Med
| accessdate = 2012-03-21 | date = 2012-03-20 | url = http://dx.doi.org/10.1371/journal.pmed.1001189 }}</ref> to 60% of some types of articles.<ref name="pmid20940209">{{cite journal| author=Eyding D, Lelgemann M, Grouven U, Härter M, Kromp M, Kaiser T et al.| title=Reboxetine for acute treatment of major depression: systematic review and meta-analysis of published and unpublished placebo and selective serotonin reuptake inhibitor controlled trials. | journal=BMJ | year= 2010 | volume= 341 | issue=  | pages= c4737 | pmid=20940209 | doi=10.1136/bmj.c4737 | pmc= | url= }} </ref><ref name="pmid15967761">{{cite journal| author=Decullier E, Lhéritier V, Chapuis F| title=Fate of biomedical research protocols and publication bias in France: retrospective cohort study. | journal=BMJ | year= 2005 | volume= 331 | issue= 7507 | pages= 19 | pmid=15967761 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=clinical.uthscsa.edu/cite&retmode=ref&cmd=prlinks&id=15967761 | doi=10.1136/bmj.38488.385995.8F | pmc=PMC558532 }} </ref><ref  name="pmid15451835">{{cite journal|  author=Chan AW, Krleza-Jerić K, Schmid I, Altman DG| title=Outcome  reporting bias in randomized trials funded by the Canadian Institutes of  Health Research. | journal=CMAJ | year= 2004 | volume= 171 | issue= 7 |  pages= 735-40 | pmid=15451835 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=15451835  | doi=10.1503/cmaj.1041086 | pmc=PMC517858 }}</ref> Publication bias may be associated with the language the study is published in and may be more common in certain areas of study. In the field of complementary and [[alternative medicine]] (CAM), publication bias may be more likely to occur in studies published in languages other than English.<ref name="pmid16086467">{{cite journal |author=Pham B, Klassen TP, Lawson ML, Moher D |title=Language of publication restrictions in systematic reviews gave different results depending on whether the intervention was conventional or complementary |journal=J Clin Epidemiol |volume=58 |issue=8 |pages=769–76 |year=2005 |pmid=16086467 |doi= |issn=
}}</ref>
 
A possible reason is that typical CAM studies are smaller than trials of conventional medicine.<ref name="pmid16086467"/> According to two European analyses, both including German authors and one from the German [[Cochrane Collaboration|Cochrane]] Center, this bias may be especially prevalent in German publications.<ref name="pmid16824217">{{cite journal |author=Galandi D, Schwarzer G, Antes G |title=The demise of the randomised controlled trial: bibliometric study of the German-language health care literature, 1948 to 2004 |journal=BMC Med Res Methodol |volume=6 |issue= |pages=30 |year=2006 |pmid=16824217 |doi=10.1186/1471-2288-6-30 |issn=}}</ref><ref name="pmid9251637">Lancet. 1997. Language bias in randomised controlled trials published in English and German. http://pubmed.gov/16086467</ref>
 
Negative studies are less likely to be published<ref name="pmid17443628">{{cite journal| author=Scherer RW, Langenberg P, von Elm E| title=Full publication of results initially presented in abstracts. | journal=Cochrane Database Syst Rev | year= 2007 | volume=  | issue= 2 | pages= MR000005 | pmid=17443628
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=17443628 | doi=10.1002/14651858.MR000005.pub3 }}</ref><ref name="pmid8015133">{{cite journal| author=Scherer RW, Dickersin K, Langenberg P| title=Full publication of results initially presented in abstracts. A meta-analysis. | journal=JAMA | year= 1994 | volume= 272 | issue= 2 | pages= 158-62 | pmid=8015133
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=8015133 }}</ref> and have more delays in their publication<ref name="pmid17443632">{{cite journal| author=Hopewell S, Clarke M, Stewart L, Tierney J| title=Time to publication for results of clinical trials. | journal=Cochrane Database Syst Rev | year= 2007 | volume=  | issue= 2 | pages= MR000011 | pmid=17443632
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=17443632 | doi=10.1002/14651858.MR000011.pub2 }}</ref>.
 
===Studies of diagnostic tests===
Publication bias may occur in studies of [[diagnostic test]]s.<ref name="pmid8610949">{{cite journal |author=Owens DK, Holodniy M, Garber AM, ''et al'' |title=Polymerase chain reaction for the diagnosis of HIV infection in adults. A meta-analysis with recommendations for clinical practice and study design |journal=Ann. Intern. Med. |volume=124 |issue=9 |pages=803–15 |year=1996 |month=May |pmid=8610949 |doi= |url=http://www.annals.org/cgi/pmidlookup?view=long&pmid=8610949 |issn=}}</ref> Publication bias may be more of a problem in diagnostic test research than in randomized controlled trials because studies of diagnostic tests can be secondary analyses of databases and do not have to be registered prior to publication.<ref name="pmid7853038">{{cite journal |author=Irwig L, Macaskill P, Glasziou P, Fahey M |title=Meta-analytic methods for diagnostic test accuracy |journal=J Clin Epidemiol |volume=48 |issue=1 |pages=119–30; discussion 131–2 |year=1995 |month=January |pmid=7853038 |doi= |url=http://linkinghub.elsevier.com/retrieve/pii/0895-4356(94)00099-C |issn=}}</ref>
 
==Detection==
In [[meta-analysis|meta-analyses]] of [[randomized controlled trial]]s, a file drawer<ref name="pmid11523382">{{cite journal |author=Pham B ''et al.'' |title=Is there a "best" way to detect and minimize publication bias? An empirical evaluation |journal=Evaluation & the Health Professions |volume=24  |pages=109–25 |year=2001 |pmid=11523382 |doi=}}</ref>, a funnel plot analysis<ref name="pmid9310563">{{cite journal |author=Egger M ''et al.'' |title=Bias in meta-analysis detected by a simple, graphical test |journal=BMJ |volume=315 |pages=629–34 |year=1997 |pmid=9310563|url=http://www.bmj.com/cgi/content/full/315/7109/629 |doi=|pmc=PMC2127453}}</ref><ref name="pmid16085192"/>, or a contour enhanced funnel plot<ref>{{Cite journal
| doi = 10.1136/bmj.b2981
| volume = 339
| issue = aug07_1
| pages = b2981
| last = Moreno
| first = Santiago G
| coauthors = Alex J Sutton, Erick H Turner, Keith R Abrams, Nicola J Cooper, Tom M Palmer, A E Ades
| title = Novel methods to deal with publication biases: secondary analysis of antidepressant trials in the FDA trial registry database and related journal publications
| journal = BMJ
| accessdate = 2009-08-13
| date = 2009-08-07
| url = http://www.bmj.com/cgi/content/abstract/339/aug07_1/b2981
}}</ref> may help detect underlying publication bias among the studies in the meta-analysis. However, other factors may cause asymmetry<ref name="pmid10812319">{{cite journal| author=Tang JL, Liu JL| title=Misleading funnel plot for detection of bias in meta-analysis. | journal=J Clin Epidemiol | year= 2000 | volume= 53 | issue= 5 | pages= 477-84 | pmid=10812319 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10812319  }} </ref> and the interpretation of the graph is subjective and inconsistent<ref name="pmid16085192">{{cite journal| author=Terrin N, Schmid CH, Lau J| title=In an empirical evaluation of the funnel plot, researchers could not visually identify publication bias. | journal=J Clin Epidemiol | year= 2005 | volume= 58 | issue= 9 | pages= 894-901 | pmid=16085192 | doi=10.1016/j.jclinepi.2005.01.006 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16085192  }} </ref>.
 
In [[meta-analysis]] of [[diagnostic test]]s, the effective sample size funnel plot and associated regression test of asymmetry may be used.<ref name="pmid16085191">{{cite journal |author=Deeks JJ, Macaskill P, Irwig L |title=The performance of tests of publication bias and other sample size effects in systematic reviews of diagnostic test accuracy was assessed |journal=J Clin Epidemiol |volume=58 |issue=9 |pages=882–93 |year=2005 |month=September |pmid=16085191 |doi=10.1016/j.jclinepi.2005.01.016 |url=http://linkinghub.elsevier.com/retrieve/pii/S0895-4356(05)00142-3 |issn=}}</ref>
 
==Causes==
Many factors influence publication.<ref name="pmid1727960"/><ref name="pmid12876092">{{cite journal |author=Krzyzanowska MK ''et al.''|title=Factors associated with failure to publish large randomized trials presented at an oncology meeting |journal=JAMA |volume=290 |pages=495–501 |year=2003 |pmid=12876092 |doi=10.1001/jama.290.4.495}}</ref> Publication bias may be due to authors not submitting negative studies for publication.<ref name="pmid12876092"/> This may especially be true of studies authored by industries with conflicts of interest.<ref name="pmid12775615">{{cite journal |author=Melander H, Ahlqvist-Rastad J, Meijer G, Beermann B |title=Evidence b(i)ased medicine--selective reporting from studies sponsored by pharmaceutical industry: review of studies in new drug applications |journal=BMJ |volume=326 |issue=7400 |pages=1171–3 |year=2003 |pmid=12775615 |doi=10.1136/bmj.326.7400.1171}}</ref><ref name="pmid12775614">{{cite journal |author=Lexchin J ''et al.''|title=Pharmaceutical industry sponsorship and research outcome and quality: systematic review |journal=BMJ |volume=326 |pages=1167–70 |year=2003 |pmid=12775614 |doi=10.1136/bmj.326.7400.1167}}</ref> Phase I studies may be more susceptible.<ref>{{Cite journal | doi = 10.1371/journal.pmed.1000034 | volume = 6 | issue = 2 | pages = e34 EP - | last = Decullier | first = Evelyne | coauthors = An-Wen Chan, François Chapuis | title = Inadequate Dissemination of Phase I Trials: A Retrospective Cohort Study | journal = PLoS Medicine | accessdate = 2009-02-19 | date = 2009-02-01 | url = http://dx.doi.org/10.1371%2Fjournal.pmed.1000034 }}</ref> Studies sponsored by industry are more likely to be positive.<ref name="pmid10968436">Djulbegovic B, Lacevic M, Cantor A, Fields KK, Bennett CL, Adams JR, Kuderer NM, Lyman GH. The uncertainty principle and industry-sponsored research. Lancet. 2000 Aug 19;356(9230):635-8. PMID 10968436</ref><ref name="pmid8285810">Rochon PA, Gurwitz JH, Simms RW, Fortin PR, Felson DT, Minaker KL, Chalmers TC. A study of manufacturer-supported trials of nonsteroidal anti-inflammatory drugs in the treatment of arthritis. Arch Intern Med. 1994 Jan 24;154(2):157-63. PMID 8285810</ref>
 
It is not simple to get a study published in any peer-reviewed journal, least of all in the best [[academic journal|journals]]. Accordingly, many studies go unreported. It is often thought to be difficult to publish small studies, the outcome of which conflicts with the reported outcomes of larger previously published studies, or to publish studies from which no clear conclusion can be drawn. In part, this reflects the wish of the best [[academic journal|journals]] to publish influential papers, and in part it reflects authors choosing not to publish studies that are thought to be uninteresting. Such ''publication bias'' can be difficult to recognise, but its effects tend to encourage publication of studies that support an already formed conclusion, while discouraging publication of contradictory or equivocal findings.<ref name="pmid1727960"/><ref name="pmid12876092"/>
 
==Related biases==
===Language bias===
Language bias may affect the results of [[meta-analysis|meta-analyses]].<ref name="pmid7853041">{{cite journal |author=Grégoire G, Derderian F, Le Lorier J |title=Selecting the language of the publications included in a meta-analysis: is there a Tower of Babel bias? |journal=J Clin Epidemiol |volume=48 |issue=1 |pages=159–63 |year=1995 |month=January |pmid=7853041 |doi= |url=http://linkinghub.elsevier.com/retrieve/pii/0895-4356(94)00098-B |issn=}}</ref>
 
===Availability of full text on the Internet===
;e-publication bias
Stuides sponsored by industry may be more likely to be published with open access by journals with hybrid publication models.<ref name="pmid20427450">{{cite journal| author=Jakobsen AK, Christensen R, Persson R, Bartels EM, Kristensen LE| title=And now, e-publication bias. | journal=BMJ | year= 2010 | volume= 340 | issue=  | pages= c2243 | pmid=20427450
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=clinical.uthscsa.edu/cite&retmode=ref&cmd=prlinks&id=20427450 | doi=10.1136/bmj.c2243 }} </ref>
 
;Full Text On the Net (FUTON) bias
Full Text On the Net (FUTON) bias may affect results of information retrieval.<ref name="pmid12401287">{{cite journal |author=Wentz R |title=Visibility of research: FUTON bias |journal=Lancet |volume=360 |issue=9341 |pages=1256 |year=2002 |month=October |pmid=12401287 |doi=10.1016/S0140-6736(02)11264-5 |url=http://linkinghub.elsevier.com/retrieve/pii/S0140-6736(02)11264-5 |issn=}}</ref>
 
===No abstract available (NAA) bias===
Certain knowledge domains may be more susceptible to 'no abstract available' (NAA) bias.<ref name="pmid12401287">{{cite journal |author=Wentz R |title=Visibility of research: FUTON bias |journal=Lancet |volume=360 |issue=9341 |pages=1256 |year=2002 |month=October |pmid=12401287 |doi=10.1016/S0140-6736(02)11264-5 |url=http://linkinghub.elsevier.com/retrieve/pii/S0140-6736(02)11264-5 |issn=}}</ref>
 
===Selective outcome reporting bias===
Among published articles, analyses of outcomes reported to be studied in unpublished protocols<ref name="pmid15161896">{{cite journal| author=Chan AW, Hróbjartsson A, Haahr MT, Gøtzsche PC, Altman DG| title=Empirical evidence for selective reporting of outcomes in randomized trials: comparison of protocols to published articles. | journal=JAMA | year= 2004 | volume= 291 | issue= 20 | pages= 2457-65 | pmid=15161896
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=clinical.uthscsa.edu/cite&retmode=ref&cmd=prlinks&id=15161896 | doi=10.1001/jama.291.20.2457 }} </ref><ref name="pmid15451835"/>, FDA submissions<ref name="pmid19067477">{{cite journal| author=Rising K, Bacchetti P, Bero L| title=Reporting bias in drug trials submitted to the Food and Drug Administration: review of publication and presentation. | journal=PLoS Med | year= 2008 | volume= 5 | issue= 11 | pages= e217; discussion e217 | pmid=19067477
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=clinical.uthscsa.edu/cite&retmode=ref&cmd=prlinks&id=19067477 | doi=10.1371/journal.pmed.0050217 | pmc=PMC2586350 }} </ref>, trial registration<ref>{{Cite journal | doi = 10.1001/jama.2009.1242 | volume = 302 | issue = 9 | pages = 977-984 | last = Mathieu | first = Sylvain | coauthors = Isabelle Boutron, David Moher, Douglas G. Altman, Philippe Ravaud | title = Comparison of Registered and Published Primary Outcomes in Randomized Controlled Trials
| journal = JAMA | accessdate = 2009-09-01 | date = 2009-09-02 | url = http://jama.ama-assn.org/cgi/content/abstract/302/9/977 }}</ref>, or the methods sections of published papers<ref name="pmid15681569">{{cite journal |author=Chan AW, Altman DG |title=Identifying outcome reporting bias in randomised trials on PubMed: review of publications and survey of authors |journal=BMJ |volume=330 |issue=7494 |pages=753 |year=2005 |month=April |pmid=15681569 |pmc=555875 |doi=10.1136/bmj.38356.424606.8F |url=http://bmj.com/cgi/pmidlookup?view=long&pmid=15681569 |issn=}}</ref> compared to the outcomes actually reported in the results of published papers found that outcomes with significant p-values are more likely to be reported, and reported sufficiently to allow inclusion in [[meta-analysis]], than insignificant outcomes.
 
Selective  outcome reporting bias may cause results of meta-analyses to be exaggerated.<ref name="pmid20156912">{{cite journal| author=Kirkham JJ, Dwan KM, Altman DG, Gamble C, Dodd S, Smyth R et al.| title=The impact of outcome reporting bias in randomised controlled trials on a cohort of systematic reviews. | journal=BMJ | year= 2010 | volume= 340 | issue=  | pages= c365 | pmid=20156912
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=clinical.uthscsa.edu/cite&email=badgett@uthscdsa.edu&retmode=ref&cmd=prlinks&id=20156912 | doi=10.1136/bmj.c365 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref>
 
==Impact of publication bias==
===Impact on meta-analysis===
Publication bias is a major threat to the validity of [[meta-analysis]]. Publication bias against negative studies may threaten the validity of [[meta-analysis|meta-analyses]] that are positive and all the studies included within the meta-analysis are small.<ref name="pmid10845965">{{cite journal |author=Sutton AJ, Duval SJ, Tweedie RL, Abrams KR, Jones DR |title=Empirical assessment of effect of publication bias on meta-analyses |journal=BMJ |volume=320 |issue=7249 |pages=1574–7 |year=2000 |pmid=10845965 |doi=}}</ref><ref name="pmid9310563">{{cite journal |author=Egger M ''et al.'' |title=Bias in meta-analysis detected by a simple, graphical test |journal=BMJ |volume=315 |pages=629–34 |year=1997 |pmid=9310563|url=http://www.bmj.com/cgi/content/full/315/7109/629 |doi=|pmc=PMC2127453}}</ref>
 
In performing a [[meta-analysis|meta-analyses]], a file drawer<ref name="pmid11523382">{{cite journal |author=Pham B ''et al.'' |title=Is there a "best" way to detect and minimize publication bias? An empirical evaluation |journal=Evaluation & the Health Professions |volume=24  |pages=109–25 |year=2001 |pmid=11523382 |doi=}}</ref> or a funnel plot analysis<ref name="pmid9310563">{{cite journal |author=Egger M ''et al.'' |title=Bias in meta-analysis detected by a simple, graphical test |journal=BMJ |volume=315 |pages=629–34 |year=1997 |pmid=9310563|url=http://www.bmj.com/cgi/content/full/315/7109/629 |doi=|pmc=PMC2127453}}</ref><ref name="pmid16085192"/> may help detect underlying publication bias among the studies in the meta-analysis.
 
Publication bias has also occurred in the publication of [[randomized controlled trial]]s of [[antidepressant]]s.<ref name="pmid18199864"/>
 
===Impact on the drug approval process===
Publication bias occurs in the data submitted to the [[United States of America]] [[Food and Drug Administration]]<ref>Lee K, Bacchetti P, Sim I. Publication of Clinical Trials Supporting Successful New Drug Applications: A Literature Analysis. PLoS Medicine. 2008 Sep 1;5(9):e191 EP -. {{doi|10.1371/journal.pmed.0050191}}</ref><ref>{{Cite journal
| doi = 10.1371/journal.pmed.0050217
| volume = 5
| issue = 11
| pages = e217 EP -
| last = Rising
| first = Kristin
| coauthors = Peter Bacchetti, Lisa Bero
| title = Reporting Bias in Drug Trials Submitted to the Food and Drug Administration: Review of Publication and Presentation
| journal = PLoS Medicine
| accessdate = 2008-11-26
| date = 2008-11-01
| url = http://dx.doi.org/10.1371%2Fjournal.pmed.0050217
}}</ref> and to the Swedish drug regulatory authority<ref name="pmid12775615">{{cite journal |author=Melander H, Ahlqvist-Rastad J, Meijer G, Beermann B |title=Evidence b(i)ased medicine--selective reporting from studies sponsored by pharmaceutical industry: review of studies in new drug applications |journal=BMJ |volume=326 |issue=7400 |pages=1171–3 |year=2003 |pmid=12775615 |doi=10.1136/bmj.326.7400.1171}}</ref>by drug companies.
 
===Impact on media coverage of scientific research===
In [[journalism]], the media is more likely to cover studies that report positive results.<ref name="pmid1890712">{{cite journal |author=Koren G, Klein N |title=Bias against negative studies in newspaper reports of medical research |journal=JAMA |volume=266 |issue=13 |pages=1824–6 |year=1991 |month=October |pmid=1890712 |doi= |url= |issn=}}</ref>
 
==Prevention==
 
===Trial registration===
In 2004, the International Committee of Medical Journal Editors (ICMJE) announced that all trials starting enrollment after July 1, 2005 must be registered prior to consideration for publication in one of the 12 member journals of the Committee.<ref name="pmid15356289">{{cite journal |author=De Angelis C, Drazen JM, Frizelle FA, ''et al'' |title=Clinical trial registration: a statement from the International Committee of Medical Journal Editors |journal=The New England journal of medicine |volume=351 |issue=12 |pages=1250–1 |year=2004 |month=September |pmid=15356289 |doi=10.1056/NEJMe048225 |url=http://content.nejm.org/cgi/pmidlookup?view=short&pmid=15356289&promo=ONFLNS19 |issn=}}</ref> [[Randomized controlled trial]]s may be registered at sites such as http://controlled-trials.com/, http://isrctn.org, and http://clinicaltrials.gov.


==References==
==References==
<references/>
<references/>[[Category:Suggestion Bot Tag]]
 
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In academic journals and scientific journals, publication bias is defined as "the influence of study results on the chances of publication and the tendency of investigators, reviewers, and editors to submit or accept manuscripts for publication based on the direction or strength of the study findings. Publication bias has an impact on the interpretation of clinical trials and meta-analyses. Bias can be minimized by insistence by editors on high-quality research, thorough literature reviews, acknowledgment of conflicts of interest, modification of peer review practices, etc."[1]

Publication bias has been documented to occur.[2]

The small study effect is closely related. The small study effect is the observation that small studies tend to report more positive results.[3][4] This is especially a threat when the original studies in a meta-analysis are less than 50 patients in size.[5]

Examples

An example of probable publication bias is in the studies of glucosamine and chondroitin for treatment of osteoarthritis. In an initial meta-analysis, the authors noted evidence of publication bias during examination of the results.[6]

A subsequent large randomized controlled trial[7] and meta-analyses including the large trial were negative.[8][9]

Another example is the selective publication of randomized controlled trials of antidepressants[10] or of positive trials in general[11].

Anecdotal examples include partial publication of results of trails of the antiviral agent oseltamivir for the prevention of influenza.[12]

Frequency of occurrence

Randomized controlled trials

Publication bias, or bias in interpretation of studies, may occur in 25%[13] to 60% of some types of articles.[14][15][16] Publication bias may be associated with the language the study is published in and may be more common in certain areas of study. In the field of complementary and alternative medicine (CAM), publication bias may be more likely to occur in studies published in languages other than English.[17]

A possible reason is that typical CAM studies are smaller than trials of conventional medicine.[17] According to two European analyses, both including German authors and one from the German Cochrane Center, this bias may be especially prevalent in German publications.[18][19]

Negative studies are less likely to be published[20][21] and have more delays in their publication[22].

Studies of diagnostic tests

Publication bias may occur in studies of diagnostic tests.[23] Publication bias may be more of a problem in diagnostic test research than in randomized controlled trials because studies of diagnostic tests can be secondary analyses of databases and do not have to be registered prior to publication.[24]

Detection

In meta-analyses of randomized controlled trials, a file drawer[25], a funnel plot analysis[26][27], or a contour enhanced funnel plot[28] may help detect underlying publication bias among the studies in the meta-analysis. However, other factors may cause asymmetry[29] and the interpretation of the graph is subjective and inconsistent[27].

In meta-analysis of diagnostic tests, the effective sample size funnel plot and associated regression test of asymmetry may be used.[30]

Causes

Many factors influence publication.[2][31] Publication bias may be due to authors not submitting negative studies for publication.[31] This may especially be true of studies authored by industries with conflicts of interest.[32][33] Phase I studies may be more susceptible.[34] Studies sponsored by industry are more likely to be positive.[35][36]

It is not simple to get a study published in any peer-reviewed journal, least of all in the best journals. Accordingly, many studies go unreported. It is often thought to be difficult to publish small studies, the outcome of which conflicts with the reported outcomes of larger previously published studies, or to publish studies from which no clear conclusion can be drawn. In part, this reflects the wish of the best journals to publish influential papers, and in part it reflects authors choosing not to publish studies that are thought to be uninteresting. Such publication bias can be difficult to recognise, but its effects tend to encourage publication of studies that support an already formed conclusion, while discouraging publication of contradictory or equivocal findings.[2][31]

Related biases

Language bias

Language bias may affect the results of meta-analyses.[37]

Availability of full text on the Internet

e-publication bias

Stuides sponsored by industry may be more likely to be published with open access by journals with hybrid publication models.[38]

Full Text On the Net (FUTON) bias

Full Text On the Net (FUTON) bias may affect results of information retrieval.[39]

No abstract available (NAA) bias

Certain knowledge domains may be more susceptible to 'no abstract available' (NAA) bias.[39]

Selective outcome reporting bias

Among published articles, analyses of outcomes reported to be studied in unpublished protocols[40][16], FDA submissions[41], trial registration[42], or the methods sections of published papers[43] compared to the outcomes actually reported in the results of published papers found that outcomes with significant p-values are more likely to be reported, and reported sufficiently to allow inclusion in meta-analysis, than insignificant outcomes.

Selective outcome reporting bias may cause results of meta-analyses to be exaggerated.[44]

Impact of publication bias

Impact on meta-analysis

Publication bias is a major threat to the validity of meta-analysis. Publication bias against negative studies may threaten the validity of meta-analyses that are positive and all the studies included within the meta-analysis are small.[45][26]

In performing a meta-analyses, a file drawer[25] or a funnel plot analysis[26][27] may help detect underlying publication bias among the studies in the meta-analysis.

Publication bias has also occurred in the publication of randomized controlled trials of antidepressants.[10]

Impact on the drug approval process

Publication bias occurs in the data submitted to the United States of America Food and Drug Administration[46][47] and to the Swedish drug regulatory authority[32]by drug companies.

Impact on media coverage of scientific research

In journalism, the media is more likely to cover studies that report positive results.[48]

Prevention

Trial registration

In 2004, the International Committee of Medical Journal Editors (ICMJE) announced that all trials starting enrollment after July 1, 2005 must be registered prior to consideration for publication in one of the 12 member journals of the Committee.[49] Randomized controlled trials may be registered at sites such as http://controlled-trials.com/, http://isrctn.org, and http://clinicaltrials.gov.

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