1. School of Medicine and Public Health, University of Newcastle, University Drive, Callaghan, NSW, Australia
2. NSW and ACT Research and Evaluation Unit, GP Synergy NSW and ACT Research and Evaluation Unit, Mayfield West, NSW, Australia
3. Clinical Research Design IT and Statistical Support, Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
4. School of Population Health, University of New South Wales, Sydney, Australia