title: Structuring and validating a cost-effectiveness model of primary asthma prevention amongst children.
abstract: BACKGROUND
  Given the rising number of asthma cases and the increasing costs of health care, prevention may be the best cure. Decisions regarding the implementation of prevention programmes in general and choosing between unifaceted and multifaceted strategies in particular are urgently needed. Existing trials on the primary prevention of asthma are, however, insufficient on their own to inform the decision of stakeholders regarding the cost-effectiveness of such prevention strategies. Decision analytic modelling synthesises available data for the cost-effectiveness evaluation of strategies in an explicit manner. Published reports on model development should provide the detail and transparency required to increase the acceptability of cost-effectiveness modelling. But, detail on the explicit steps and the involvement of experts in structuring a model is often unevenly reported. In this paper, we describe a procedure to structure and validate a model for the primary prevention of asthma in children.
  
  
  METHODS
  An expert panel was convened for round-table discussions to frame the cost-effectiveness research question and to select and structure a model. The model's structural validity, which indicates how well a model reflects the reality, was determined through descriptive and parallel validation. Descriptive validation was performed with the experts. Parallel validation qualitatively compared similarity between other published models with different decision problems.
  
  
  RESULTS
  The multidisciplinary input of experts helped to develop a decision-tree structure which compares the current situation with screening and prevention. The prevention was further divided between multifaceted and unifaceted approaches to analyse the differences. The clinical outcome was diagnosis of asthma. No similar model was found in the literature discussing the same decision problem. Structural validity in terms of descriptive validity was achieved with the experts and was supported by parallel validation.
  
  
  CONCLUSIONS
  A decision-tree model developed with experts in round-table discussions benefits from a systematic and transparent approach and the multidisciplinary contributions of the experts. Parallel validation provides a feasible alternative to validating novel models. The process of structuring and validating a model presented in this paper could be a useful guide to increase transparency, credibility, and acceptability of (future, novel) models when experts are involved.
authors: Department of General Practice, CAPHRI School for Public Health and Primary Care, Maastricht University, Maastricht, the Netherlands. feljandro.ramos@gmail.com
authors: G Feljandro P
authors: GF
authors: Ramos
authors: Sandra
authors: S
authors: Kuiper
authors: Edward
authors: E
authors: Dompeling
authors: Antoinette D I
authors: AD
authors: van Asselt
authors: Wim J C
authors: WJ
authors: de Grauw
authors: J André
authors: JA
authors: Knottnerus
authors: Onno C P
authors: OC
authors: van Schayck
authors: Tjard R J
authors: TR
authors: Schermer
authors: Johan L
authors: JL
authors: Severens
mesh_terms: D000465:Algorithms; D001249:Asthma / Q000517:prevention & control* / Q000628:therapy; D002648:Child; D003362:Cost-Benefit Analysis; D003661:Decision Support Techniques; D017048:Health Care Costs / Q000706:statistics & numerical data; D006801:Humans; D018803:Models, Economic; D011322:Primary Prevention / Q000191:economics* / Q000379:methods; D015203:Reproducibility of Results