Table 1 Inclusion criteria for out-of-hours GP cooperatives

1. Serving a population > 10,000 inhabitants

2. Advising the population to call the service on perceiving a need for medical attention out-of-hours

3. The telephone office answering the national telephone number for the out-of-hours service is localized inside the out-of-hours GP cooperative

4. Is managed by at least one nurse during evenings

5. Covers one or several entire municipalities (municipalities where the population adheres to only one out-of-hours GP cooperative)