Development of a Conceptual Model of Childhood Asthma to Inform Asthma Prevention Policies

Abstract Background There is no definitive cure for asthma; as such, prevention remains a major goal. Decision-analytic models are routinely used to evaluate the value-for-money proposition of interventions. Following best practice standards in decision-analytic modeling, the objective of this study was to solicit expert opinion to develop a concept map for a policy model for primary prevention of asthma. Methods We reviewed currently available decision-analytic models for asthma prevention. A steering committee of economic modelers, allergists, and respirologists was then convened to draft a conceptual model of pediatric asthma. A modified Delphi method was followed to define the context of the problem at hand (evaluation of asthma prevention strategies) and develop the concept map of the model. Results Consensus was achieved after three rounds of discussions, followed by concealed voting. In the final conceptual model, asthma diagnosis was based on three domains of lung function, atopy, and their symptoms. The panel recommended several markers for each domain. These domains were in turn affected by several risk factors. The panel clustered all risk factors under three groups of ‘patient characteristic’, ‘family history’, and ‘environmental factors’. To be capable of modeling the interplay among risk factors, the panel recommended the use of microsimulation, with an open-population approach that would enable modeling phased implementation and gradual and incomplete uptake of the intervention. Conclusions Economic evaluation of childhood interventions for preventing asthma will require modeling of several co-dependent risk factors and multiple domains that affect the diagnosis. The conceptual model can inform the development and validation of a policy model for childhood asthma prevention. Funding Genome Canada Large-Scale Applied Research Project