The use of statistical process control methods in monitoring clinical performance.

The use of statistical process control methods in monitoring clinical performance To the Editor: The article by Spiegelhalter and colleagues [1] and the Counterpoint papers by Benneyan and Borgman [2], Lim [3], and Bolsin and Colson [4] deserve further comment. At least two issues should be raised, the first of which, the primacy of systems, is of crucial importance. Benneyan and Borgman state that`Fostering greater and more widespread use of these methods remains a significant challenge'. In Australia, statistical process control (SPC) methods were implemented with enthusiasm in the mid-1980s, as the Australian Council on Healthcare Standards (ACHS) embarked on widespread hospital accreditation. They quickly fell into disuse because they were found not to be useful. This occurred because the role of SPC was not understood. Thus we have waited nearly 20 years for their resurrection in hospitals, albeit with much improved methods. Unless we learn from the mistakes of the mid-1980s, these very valuable methods will once again be found wanting and they will once again fall into disuse. The problem is that processes must be brought into statistical control before SPC is useful; the message that control limits are useless unless the process is in control is so fundamental that it seems easily to be forgotten. It can, of course, be argued that the risk adjustment imposes the required statistical control. I believe, however, that this problem still exists, certainly at a philosophical and quality improvement level, but also in all probability at a scientific and statistical one too. Shewhart, Deming and others have repeatedly pointed out that control limits are meaningless unless the system has first been brought into statistical control. This is eloquently described in the wonderful book by David Salsburg, The Lady Tasting Tea. How Statistics Revolutionized Science in the Twentieth Century [5]. Bringing processes into statistical control in hospitals implies that hospital systems are first carefully analysed and optimized [6-9]. All substandard performance is underpinned by unsatisfactory systems; even an incompetent operator is a system problem because the system allows him or her to operate. In Australia in the early 1980s, hospitaìreform' was in full swing under the influence of a managerialist management system obsessed with very short-term financial objectives and individual performance. The system was one of reducing costs in the short term and judging individuals, not of providing a quality service. SPC was bound to fail. Analysing and optimizing systems is a …