Moral hazard and supplier-induced demand: empirical evidence in general practice.

Changes in cost sharing and remuneration system in the Netherlands in 2006 led to clear changes in financial incentives faced by both consumers and general practitioner (GPs). For privately insured consumers, cost sharing was abolished, whereas those socially insured never faced cost sharing. The separate remuneration systems for socially insured consumers (capitation) and privately insured consumers (fee-for-service) changed to a combined system of capitation and fee-for-service for both groups. Our first hypothesis was that privately insured consumers had a higher increase in patient-initiated GP contact rates compared with socially insured consumers. Our second hypothesis was that socially insured consumers had a higher increase in physician-initiated contact rates. Data were used from electronic medical records from 32 GP-practices and 35336 consumers in 2005-2007. A difference-in-differences approach was applied to study the effect of changes in cost sharing and remuneration system on contact rates. Abolition of cost sharing led to a higher increase in patient-initiated utilisation for privately insured consumers in persons aged 65 and older. Introduction of fee-for-service for socially insured consumers led to a higher increase in physician-initiated utilisation. This was most apparent in persons aged 25 to 54. Differences in the trend in physician-initiated utilisation point to an effect of supplier-induced demand. Differences in patient-initiated utilisation indicate limited evidence for moral hazard.