Submitted on: 30 October 2005.
Revised on: 19 January 2006.
Accepted on: 17 February 2006.
___________________BMJ Open---BMJ PUBLISHING GROUP
Submitted on: 13 February 2016.
Revised on: 10 April 2016.
Accepted on: 23 May 2016.
___________________BMJ Open---BMJ PUBLISHING GROUP
Submitted on: 25 May 2024.
Revised on: 16 August 2024.
Accepted on: 11 October 2024.
___________________BMJ Open---BMJ PUBLISHING GROUP
Submitted on: 08 March 2015.
Revised on: 21 June 2015.
Accepted on: 01 July 2015.
___________________BMJ Open---BMJ PUBLISHING GROUP
Submitted on: 17 October 2012.
Revised on: 10 December 2012.
Accepted on: 21 January 2013.
___________________BMJ Open---BMJ PUBLISHING GROUP
Submitted on: 16 February 2017.
Revised on: 09 April 2017.
Accepted on: 07 May 2017.
___________________BMJ Open---BMJ PUBLISHING GROUP