Policy implications of heterogeneous demand reactions to changes in cost-sharing: Patient-level evidence from Austria.

Cost-sharing is a prominent tool in many healthcare systems, both for raising revenue and steering patient behaviour. Although the effect of cost-sharing on demand for healthcare services has been heavily studied in the literature, researchers often apply a macro-perspective to these issues, opening the door for policy makers to the fallacy of assuming uniform demand reactions across a spectrum of different forms of treatments and diagnostic procedures. We use a simple classification system to categorize 11 such healthcare services along the dimensions of urgency and price to estimate patients' (anticipatory) demand reactions to a reduction in the co-insurance rate by a sickness fund in the Austrian social health insurance system. We use a two-stage study design combining matching and two-way fixed effects difference-in-differences estimation. Our results highlight how an overall joint estimate of an average increase in healthcare service utilization (0.8%) across all healthcare services can be driven by healthcare services that are deferrable (+1%), comparatively costly (+1.4%) or both (+1.6%) and for which patients also postponed their consumption until after the cost-sharing reduction. In contrast, we do not find a clear demand reaction for inexpensive or urgent services. The detailed analysis of the demand reaction for each individual healthcare service further illustrates their heterogeneity. We show that even comparatively minor changes to the costs borne by patients may already evoke tangible (anticipatory) demand reactions. Our findings help policy makers better understand the implications of heterogeneous demand reactions across healthcare services for using cost-sharing as a policy tool.