%0 Journal Article %1 Chan2005a %A Chan, An-Wen %A Altman, Douglas G %D 2005 %J BMJ (Clinical research ed.) %K Bias(Epidemiology) DataCollection DataCollection:standards Prevalence PubMed RandomizedControlledTrialsasTopic:standards RandomizedControlledTrialsasTopic:statistics SelectionBias TreatmentOutcome RCT %N 7494 %P 753 %R 10.1136/bmj.38356.424606.8F %T Identifying outcome reporting bias in randomised trials on PubMed: review of publications and survey of authors. %U http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=555875&tool=pmcentrez&rendertype=abstract %V 330 %X OBJECTIVE: To examine the extent and nature of outcome reporting bias in a broad cohort of published randomised trials. DESIGN: Retrospective review of publications and follow up survey of authors. Cohort All journal articles of randomised trials indexed in PubMed whose primary publication appeared in December 2000. MAIN OUTCOME MEASURES: Prevalence of incompletely reported outcomes per trial; reasons for not reporting outcomes; association between completeness of reporting and statistical significance. RESULTS: 519 trials with 553 publications and 10,557 outcomes were identified. Survey responders (response rate 69%) provided information on unreported outcomes but were often unreliable--for 32% of those who denied the existence of such outcomes there was evidence to the contrary in their publications. On average, over 20% of the outcomes measured in a parallel group trial were incompletely reported. Within a trial, such outcomes had a higher odds of being statistically non-significant compared with fully reported outcomes (odds ratio 2.0 (95% confidence interval 1.6 to 2.7) for efficacy outcomes; 1.9 (1.1 to 3.5) for harm outcomes). The most commonly reported reasons for omitting efficacy outcomes included space constraints, lack of clinical importance, and lack of statistical significance. CONCLUSIONS: Incomplete reporting of outcomes within published articles of randomised trials is common and is associated with statistical non-significance. The medical literature therefore represents a selective and biased subset of study outcomes, and trial protocols should be made publicly available.

@article{Chan2005a, abstract = {OBJECTIVE: To examine the extent and nature of outcome reporting bias in a broad cohort of published randomised trials. DESIGN: Retrospective review of publications and follow up survey of authors. Cohort All journal articles of randomised trials indexed in PubMed whose primary publication appeared in December 2000. MAIN OUTCOME MEASURES: Prevalence of incompletely reported outcomes per trial; reasons for not reporting outcomes; association between completeness of reporting and statistical significance. RESULTS: 519 trials with 553 publications and 10,557 outcomes were identified. Survey responders (response rate 69%) provided information on unreported outcomes but were often unreliable--for 32% of those who denied the existence of such outcomes there was evidence to the contrary in their publications. On average, over 20% of the outcomes measured in a parallel group trial were incompletely reported. Within a trial, such outcomes had a higher odds of being statistically non-significant compared with fully reported outcomes (odds ratio 2.0 (95% confidence interval 1.6 to 2.7) for efficacy outcomes; 1.9 (1.1 to 3.5) for harm outcomes). The most commonly reported reasons for omitting efficacy outcomes included space constraints, lack of clinical importance, and lack of statistical significance. CONCLUSIONS: Incomplete reporting of outcomes within published articles of randomised trials is common and is associated with statistical non-significance. The medical literature therefore represents a selective and biased subset of study outcomes, and trial protocols should be made publicly available.}, added-at = {2023-02-03T11:44:35.000+0100}, author = {Chan, An-Wen and Altman, Douglas G}, biburl = {https://www.bibsonomy.org/bibtex/27943e81b7a36c64468ea3a1f5291c97a/jepcastel}, doi = {10.1136/bmj.38356.424606.8F}, interhash = {2e86aef74c6b168d8be79cb6a27b269e}, intrahash = {7943e81b7a36c64468ea3a1f5291c97a}, issn = {1756-1833}, journal = {BMJ (Clinical research ed.)}, keywords = {Bias(Epidemiology) DataCollection DataCollection:standards Prevalence PubMed RandomizedControlledTrialsasTopic:standards RandomizedControlledTrialsasTopic:statistics SelectionBias TreatmentOutcome RCT}, month = {4}, note = {3787<m:linebreak></m:linebreak>Publicació}, number = 7494, pages = 753, pmid = {15681569}, timestamp = {2023-05-04T08:59:38.000+0200}, title = {Identifying outcome reporting bias in randomised trials on PubMed: review of publications and survey of authors.}, url = {http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=555875&tool=pmcentrez&rendertype=abstract}, volume = 330, year = 2005 }