“…A number of studies reported substantial improvement in quality both in inpatient [1,11,14,18,21,32,50,53,57,60,62,68,78] and outpatient settings [13,29,37,40,42,46]. Numerous studies, including six RCTs [4,7,38,51,63,71], failed to show any positive effects on quality associated with practice guidelines [5,10,20,25,26,36]. Results were mixed in 12 studies, in which practice guidelines improved quality for certain outcomes or patient subgroups but not others [8,23,24,41,43,52,54,55,58,59,73,74].…”