Andersson et al. BMC Public Health 2011, 11:215 http://www.biomedcentral.com/1471-2458/11/215 Research, VU University Medical Centre, Amsterdam, Netherlands. 3Centre of Prevention and Early Intervention, Trimbos Institute (Netherlands Institute of Mental Health and Addiction), Utrecht, Netherlands. 4Department of Behavioural Sciences and Learning, Swedish Institute for Disability Research, Linköping University, Sweden. Authors’ contributions EA was main responsible in interpreting health economic data and performed all statistical analyses. He also performed psychiatric interviews in the study and was responsible for drafting this manuscript. BL was the study project manager. He wrote the treatment manual and participated in the drafting of this manuscript. FS participated in the interpretation of health economic data and statistical analyses. He also contributed to the drafting of the manuscript. BP crosschecked all health economic data and participated in the statistical analyses. He also contributed to the drafting of the manuscript. EH participated in the conception of the study and in revising this manuscript. NL participated in the study conception, its design and management, analysis of data, interpretation and revising this manuscript. GA participated in the study conception, its design and management, analysis of data, interpretation and revising this manuscript. CR participated in the conception of the study and its design, was responsible for psychiatric assessments and in the supervising of this manuscript. All authors read and approved the final manuscript. Competing interests The authors declare that they have no competing interests. Received: 8 November 2010 Accepted: 7 April 2011 Published: 7 April 2011 References 1. Lacy BE, Lee RD: Irritable bowel syndrome: a syndrome in evolution. J Clin Gastroenterol 2005, 39(5 Suppl 3):S230-42. 2. Drossman DA, et al: U.S. householder survey of functional gastrointestinal disorders. 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Pre-publication history The pre-publication history for this paper can be accessed here: http://www.biomedcentral.com/1471-2458/11/215/prepub doi:10.1186/1471-2458-11-215 Cite this article as: Andersson et al.: Cost-effectiveness of internet-based cognitive behavior therapy for irritable bowel syndrome: results from a randomized controlled trial. BMC Public Health 2011 11:215.