RT Journal Article SR Electronic T1 Correction JF BMJ Quality & Safety JO BMJ Qual Saf FD BMJ Publishing Group Ltd SP 182 OP 182 DO 10.1136/bmjqs.2011.051755 VO 22 IS 2 YR 2013 UL http://qualitysafety.bmj.com/content/22/2/182.6.abstract AB