Implementation of a general practitioner cooperative adjacent to the emergency department of a hospital increases the caseload for the GPC but not for the emergency department.

Background: The implementation of general practitioner cooperatives (GPC) for out-of-hours (OOH) primary care, raises the question if the location of a GPC adjacent to a hospital reduces the OOH caseload of the emergency department (ED).

Methods: Two natural experiments were used in this before-after study, the effect of the implementation of two GPCs in two different regions on the out-of-hours caseload of the local EDs was compared. One GPC was located adjacent to the ED of a general hospital, the other was not. GPCs (or rota systems) and EDs in comparable regions were selected as control groups during the same study period. The study was performed in Flanders (Belgium) with no gatekeeping function for general practitioners (GPs).

Results: After implementation of the GPC there was a significantly increase in caseload at the GPC in the two regions, mainly due to an increase of consultations with small children. There were no significant changes in caseload at the ED services. Self-referrals' to the ED did not change significantly. For the GPs the number of home visits decreased during out-of-hours in one region.

Conclusion: In a country with no gatekeeping role for GPs, implementing a GPC increased the out-of-hours caseload of the GPCs. The caseload of the EDs stabilised during the study period.