PT - JOURNAL ARTICLE ED - , TI - Correction AID - 10.1136/bmjopen-2013-003574corr1 DP - 2013 Dec 01 TA - BMJ Open PG - e003574corr1 VI - 3 IP - 12 4099 - http://bmjopen.bmj.com/content/3/12/e003574corr1.short 4100 - http://bmjopen.bmj.com/content/3/12/e003574corr1.full SO - BMJ Open2013 Dec 01; 3