The value of health interventions: evaluating asthma case management using matching

Despite large public investments in asthma interventions, there are few rigorous assessments of these programmes and little understanding of what comprises an effective intervention. There is a lack of appropriate data, little technical support is provided, and the programs themselves have little incentive to conduct these analyses. In this study, we apply optimal full matching using propensity scores to estimate the impact of an asthma intervention programme across a range of health outcomes. Our participation model is derived using the Deletion, Substitution and Addition (DSA) algorithm, a method used in epidemiology for model selection. We find that the asthma programme in question has no significant effect on participants that distinguishes them from matched nonparticipants, but it is not clear whether this is due to the effectiveness of the programme, heterogeneity of effects or barriers outside the programme's control. Our findings do show how current programmes could be modified to increase their effectiveness and better inform future research.