**Conflict of interest**

David Johnson has previously received consultancy fees, research grants, speaker's honoraria and travel sponsorships from Baxter Healthcare and Fresenius Medical Care. He has also received consultancy fees from Astra Zeneca and travel sponsorships from Amgen. He is a current recipient of an Australian National Health and Medical Research Council Practitioner Fellowship. Carmel Hawley has received a research grant from Baxter Healthcare. Ross Francis has received honoraria and travel sponsorships from Novartis, Astellas and Amgen. The other authors have no conflict of interest to declare.
