Changing GPs' antibiotic prescribing: a randomised controlled trial

A randomised controlled trial involving 54 general practitioners (GPs) was conducted in Canberra, Australian Capital Territory from September 1997 to November 1999. In the first year of the study, 24 GPs, who constituted the active arm of the intervention group, were involved in the consideration of evidence and the development and implementation of a set of clinical guidelines for the treatment of acute respiratory infections. These guidelines were then endorsed in a meeting together with specialist colleagues. In the second year of the study the group of GPs who had been acting as controls, received a moderate intervention consisting of a brief educational event and distribution of the locally developed guidelines. We obtained data from January 1997 to December 1999 from the Health Insurance Commission on prescribing rates for 40 of the doctors in the study. The rate of prescribing was calculated as the number of antibiotic prescriptions per 100 Medicare services. The average yearly prescribing decreased significantly in the intensive intervention group and increased in the moderate intervention group, (p=0.026). A mixed effects longitudinal time series model was fitted to the data to account for seasonal variation of antibiotic prescribing and trends over time. The intensive intervention group significantly reduced their antibiotic prescribing over time compared to the moderate intervention group, (p<0.001). This study has shown that an intensive intervention in which general practitioners were actively engaged in development and consideration of the evidence base for the guidelines resulted in a significant fall in general antibiotic prescribing.