title: Positive outcomes influence the rate and time to publication, but not the impact factor of publications of clinical trial results.
abstract: OBJECTIVE
  Publication bias may affect the validity of evidence based medical decisions. The aim of this study is to assess whether research outcomes affect the dissemination of clinical trial findings, in terms of rate, time to publication, and impact factor of journal publications.
  
  
  RESULTS
  All drug-evaluating clinical trials submitted to and approved by a general hospital ethics committee between 1997 and 2004 were prospectively followed to analyze their fate and publication. Published articles were identified by searching Pubmed and other electronic databases. Clinical study final reports submitted to the ethics committee, final reports synopses available online and meeting abstracts were also considered as sources of study results. Study outcomes were classified as positive (when statistical significance favoring experimental drug was achieved), negative (when no statistical significance was achieved or it favored control drug) and descriptive (for non-controlled studies). Time to publication was defined as time from study closure to publication. A survival analysis was performed using a Cox regression model to analyze time to publication. Journal impact factors of identified publications were recorded. Publication rate was 48·4% (380/785). Study results were identified for 68·9% of all completed clinical trials (541/785). Publication rate was 84·9% (180/212) for studies with results classified as positive and 68·9% (128/186) for studies with results classified as negative (p<0·001). Median time to publication was 2·09 years (IC95 1·61-2·56) for studies with results classified as positive and 3·21 years (IC95 2·69-3·70) for studies with results classified as negative (hazard ratio 1·99 (IC95 1·55-2·55). No differences were found in publication impact factor between positive (median 6·308, interquartile range: 3·141-28·409) and negative result studies (median 8·266, interquartile range: 4·135-17·157).
  
  
  CONCLUSIONS
  Clinical trials with positive outcomes have significantly higher rates and shorter times to publication than those with negative results. However, no differences have been found in terms of impact factor.
authors: Pharmacy Department, Hospital Universitari Vall d'Hebron, Barcelona, Spain. psune@vhebron.net
authors: Pilar
authors: P
authors: Suñé
authors: Josep Maria
authors: JM
authors: Suñé
authors: J Bruno
authors: JB
authors: Montoro
mesh_terms: D002986:Clinical Trials as Topic; D019317:Evidence-Based Medicine / Q000592:standards; D006801:Humans; D055811:Journal Impact Factor; D017594:Publication Bias; D011642:Publications / Q000592:standards* / Q000706:statistics & numerical data*; D013997:Time Factors; D016896:Treatment Outcome
references: Trials. 2010 Apr 13;11:37
references: 20388211
references: Arch Pediatr Adolesc Med. 2005 Nov;159(11):1036-7
references: 16275793
references: J Bone Joint Surg Am. 2008 Mar;90(3):595-601
references: 18310710
references: PLoS Med. 2008 Sep 23;5(9):e191
references: 18816163
references: J Eval Clin Pract. 2002 Aug;8(3):353-9
references: 12164983
references: Med J Aust. 2006 Jun 19;184(12):621-6
references: 16803442
references: BMJ. 2008 Dec 04;337:a2299
references: 19056791
references: J Med Libr Assoc. 2003 Jan;91(1):42-6
references: 12572533
references: Cochrane Database Syst Rev. 2007 Apr 18;(2):MR000011
references: 17443632
references: Lancet. 1991 Apr 13;337(8746):867-72
references: 1672966
references: Swiss Med Wkly. 2008 Apr 5;138(13-14):197-203
references: 18389392
references: J Clin Oncol. 1986 Oct;4(10):1529-41
references: 3760920
references: BMJ. 2011 Apr 05;342:d1828
references: 21467104
references: J Bone Joint Surg Am. 2007 May;89(5):1010-8
references: 17473138
references: Invest New Drugs. 2009 Jun;27(3):287-8
references: 18931825
references: BMJ. 2005 Apr 23;330(7497):956-8
references: 15845980
references: Online J Curr Clin Trials. 1993 Apr 28;Doc No 50:[4967 words; 53 paragraphs]
references: 8306005
references: Cochrane Database Syst Rev. 2009 Jan 21;(1):MR000006
references: 19160345
references: JAMA. 1998 Jul 15;280(3):257-9
references: 9676674
references: JAMA. 2009 Sep 2;302(9):977-84
references: 19724045
references: JAMA. 1992 Jan 15;267(3):374-8
references: 1727960
references: JAMA. 1998 Jan 28;279(4):281-6
references: 9450711
references: JAMA. 1996 Aug 28;276(8):637-9
references: 8773637
references: PLoS One. 2008 Aug 28;3(8):e3081
references: 18769481
references: BMJ. 2005 Jul 2;331(7507):19
references: 15967761
references: BMJ. 1997 Sep 13;315(7109):640-5
references: 9310565
references: JAMA. 2002 Jun 5;287(21):2825-8
references: 12038924
references: JAMA. 1998 Jan 28;279(4):319-20
references: 9450719
references: JAMA. 2004 May 26;291(20):2457-65
references: 15161896
references: JAMA. 2004 Sep 15;292(11):1363-4
references: 15355936
references: JAMA. 2003 Jul 23;290(4):516-23
references: 12876095
references: Health Technol Assess. 2010 Feb;14(8):iii, ix-xi, 1-193
references: 20181324