title: Unremarked or Unperformed? Systematic Review on Reporting of Validation Efforts of Health Economic Decision Models in Seasonal Influenza and Early Breast Cancer.
abstract: Transparent reporting of validation efforts of health economic models give stakeholders better insight into the credibility of model outcomes. In this study we reviewed recently published studies on seasonal influenza and early breast cancer in order to gain insight into the reporting of model validation efforts in the overall health economic literature.
  
  
  
  A literature search was performed in Pubmed and Embase to retrieve health economic modelling studies published between 2008 and 2014. Reporting on model validation was evaluated by checking for the word validation, and by using AdViSHE (Assessment of the Validation Status of Health Economic decision models), a tool containing a structured list of relevant items for validation. Additionally, we contacted corresponding authors to ask whether more validation efforts were performed other than those reported in the manuscripts.
  
  
  
  A total of 53 studies on seasonal influenza and 41 studies on early breast cancer were included in our review. The word validation was used in 16 studies (30 %) on seasonal influenza and 23 studies (56 %) on early breast cancer; however, in a minority of studies, this referred to a model validation technique. Fifty-seven percent of seasonal influenza studies and 71 % of early breast cancer studies reported one or more validation techniques. Cross-validation of study outcomes was found most often. A limited number of studies reported on model validation efforts, although good examples were identified. Author comments indicated that more validation techniques were performed than those reported in the manuscripts.
  
  
  
  Although validation is deemed important by many researchers, this is not reflected in the reporting habits of health economic modelling studies. Systematic reporting of validation efforts would be desirable to further enhance decision makers' confidence in health economic models and their outcomes.
authors.affiliation: Department of Pharmacy, PharmacoTherapy, -Epidemiology and -Economics (PTEE), University of Groningen, Groningen, The Netherlands.
authors.forename: Pieter T
authors.initials: PT
authors.lastname: de Boer
authors.affiliation: Pharmacoepidemiology and Clinical Pharmacology, University of Utrecht, Utrecht, The Netherlands.
authors.forename: Geert W J
authors.initials: GW
authors.lastname: Frederix
authors.affiliation: Department of Epidemiology, University Medical Center Groningen, University of Groningen, PO Box 30.001, 9700 RB, Groningen, The Netherlands.|Centre for Nutrition, Prevention and Health Services Research, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Talitha L
authors.initials: TL
authors.lastname: Feenstra
authors.affiliation: Department of Pharmacy, PharmacoTherapy, -Epidemiology and -Economics (PTEE), University of Groningen, Groningen, The Netherlands. p.vemer@rug.nl.|Department of Epidemiology, University Medical Center Groningen, University of Groningen, PO Box 30.001, 9700 RB, Groningen, The Netherlands. p.vemer@rug.nl.
authors.forename: Pepijn
authors.initials: P
authors.lastname: Vemer
mesh_terms: D001943:Breast Neoplasms / Q000191:economics*; D003657:Decision Making; D003661:Decision Support Techniques; D005260:Female; D006801:Humans; D007251:Influenza, Human / Q000191:economics*; D018803:Models, Economic; D012107:Research Design; D054928:Validation Studies as Topic