Abstract
Background and Aims
Little is known about the extent and nature of publication bias in economic evaluations. Our objective was to determine whether economic evaluations are subject to publication bias by considering whether economic data are as likely to be reported, and reported as promptly, as effectiveness data.
Methods
Trials that intended to conduct an economic analysis and ended before 2008 were identified in the International Standard Randomised Controlled Trial Number (ISRCTN) register; a random sample of 100 trials was retrieved. Fifty comparator trials were randomly drawn from those not identified as intending to conduct an economic study. The trial start and end dates, estimated sample size and funder type were extracted. For trials planning economic evaluations, effectiveness and economic publications were sought; publication dates and journal impact factors were extracted. Effectiveness abstracts were assessed for whether they reached a firm conclusion that one intervention was most effective. Primary investigators were contacted about reasons for non-publication of results, or reasons for differential publication strategies for effectiveness and economic results.
Results
Trials planning an economic study were more likely to be funded by government (p = 0.01) and larger (p = 0.003) than other trials. The trials planning an economic evaluation had a mean of 6.5 (range 2.7–13.2) years since the trial end in which to publish their results. Effectiveness results were reported by 70 %, while only 43 % published economic evaluations (p < 0.001). Reasons for non-publication of economic results included the intervention being ineffective, and staffing issues. Funding source, time since trial end and length of study were not associated with a higher probability of publishing the economic evaluation. However, studies that were small or of unknown size were significantly less likely to publish economic evaluations than large studies (p < 0.001). The authors’ confidence in labelling one intervention clearly most effective did not affect the probability of publication. The mean time to publication was 0.7 years longer for cost-effectiveness data than for effectiveness data where both were published (p = 0.001). The median journal impact factor was 1.6 points higher for effectiveness publications than for the corresponding economic publications (p = 0.01). Reasons for publishing in different journals included editorial decision making and the additional time that economic evaluation takes to conduct.
Conclusions
Trials that intend to conduct an economic analysis are less likely to report economic data than effectiveness data. Where economic results do appear, they are published later, and in journals with lower impact factors. These results suggest that economic output may be more susceptible than effectiveness data to publication bias. Funders, grant reviewers and trialists themselves should ensure economic evaluations are prioritized and adequately staffed to avoid potential problems with bias.
Similar content being viewed by others
References
Dwan K, Altman DG, Arnaiz JA, et al. Systematic review of the empirical evidence of study publication bias and outcome reporting bias. PLoS One. 2008;3(8):e3081.
Hopewell S, Clarke M, Stewart L, et al. Time to publication for results of clinical trials. Cochrane Database of Systematic Reviews 2007;2:MR000011.
Littner Y, Mimouni FB, Dollberg S, et al. Negative results and impact factor: a lesson from neonatology. Arch Pediatr Adolesc Med. 2005;159(11):1036–7.
Sacristán JA, Bolaños E, Hernández JM, et al. Publication bias in health economic studies. PharmacoEconomics. 1997;11(3):289–92.
Bell CM, Urbach DR, Ray JG, et al. Bias in published cost effectiveness studies: systematic review. BMJ. 2006;332(7543):699–703.
Gilbody S, Bower P, Sutton AJ. Randomized trials with concurrent economic evaluations reported unrepresentatively large clinical effect sizes. J Clin Epidemiol. 2007;60(8):781–6.
Stoykova B, Drummond M, Barbieri M, et al. The lag between effectiveness and cost-effectiveness evidence of new drugs. Eur J Health Econ. 2003;4(4):313–8.
Greenberg D, Rosen AB, Olchanski NV, et al. Delays in publication of cost utility analyses conducted alongside clinical trials: registry analysis. BMJ. 2004;328(7455):1536–7.
WHO. WHO trial registration data set (version 1.2.1). WHO: Geneva; 2011 http://www.who.int/ictrp/network/trds/en/index.html. Accessed 11 Jul 2011.
Ntonas K, Kokkoras F. DEiXTo. http://www.deixto.com/. Accessed 11 Jul 2011.
Song F, Eastwood AJ, Gilbody S, et al. Publication and related biases. Health Technol Assess. 2000;4(10):1–115.
Miners AH, Garau M, Fidan D, et al. Comparing estimates of cost effectiveness submitted to the National Institute for Clinical Excellence (NICE) by different organisations: retrospective study. BMJ. 2005;330(7482):65.
Garattini L, Koleva D, Casadei G. Modeling in pharmacoeconomic studies: funding sources and outcomes. Int J Technol Assess Health Care. 2010;26:330–3.
John-Baptiste A, Bell C. Industry sponsored bias in cost effectiveness analyses. BMJ. 2010;341:c5350.
Egger M, Smith GD, Schneider M, et al. Bias in meta-analysis detected by a simple, graphical test. BMJ. 1997;315(7109):629–34.
Bian ZX, Wu TX. Legislation for trial registration and data transparency. Trials. 2010;11(1):64.
Ross JS, Mulvey GK, Hines EM, et al. Trial publication after registration in ClinicalTrials.Gov: a cross-sectional analysis. PLoS Med. 2009;6(9):e1000144.
Stata [computer program]. Version 11. College Station: StataCorp LP; 2009.
Acknowledgements
The authors thank Dr Lisa Hampson for her assistance with the statistical analyses. This work was supported by the Medical Research Council (grant number G0800800) as part of the Network of Hubs for Trials Methodology Research (ConDuCT Hub).
Author Contributions
WH and SN initiated and designed the study; JT collected and extracted the data and carried out the statistical analysis. All authors contributed to interpretation of the data and to the final manuscript. JT is the study guarantor.
Author information
Authors and Affiliations
Corresponding author
Electronic supplementary material
Below is the link to the electronic supplementary material.
Rights and permissions
About this article
Cite this article
Thorn, J.C., Noble, S.M. & Hollingworth, W. Timely and Complete Publication of Economic Evaluations Alongside Randomized Controlled Trials. PharmacoEconomics 31, 77–85 (2013). https://doi.org/10.1007/s40273-012-0004-7
Published:
Issue Date:
DOI: https://doi.org/10.1007/s40273-012-0004-7