1 The Systematic Review Unit, The Collaborative Research (CORE) Group, Macquarie University, Sydney, Australia.
2 Department of Cardiothoracic Surgery, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
3 The Systematic Review Unit, The Collaborative Research (CORE) Group, Macquarie University, Sydney, Australia; Department of Cardiothoracic Surgery, The Royal Prince Alfred Hospital, Sydney, Australia.