Funnel plots and their emerging application in surgery.
OBJECTIVE
To familiarize surgeons with the use of funnel plots as a control tool to assess quality in surgery.


BACKGROUND
Surgical outcomes are an important component of quality in healthcare delivery. Several control tools have been introduced and tested including the use of graphical tools such as funnel plots. More recently, their application in healthcare to assess quality has become more evident. Ranking in surgical performance has significant limitations, risks, and implications which can be addressed by the use of funnel plots.


METHODS
This methodological review explores the principles and existing application of funnel plots within surgery and emphasizes their advantages, limitations, public health implications, and their use to assess the evidence in the literature and potential future applications.


RESULTS
Funnel plots are practical tools, easy to use, and offer the opportunity to statistically define control limits around measurable outcomes, allowing for adjustment of unmeasured factors. This makes them extremely useful for the monitoring of performance in surgery either at a surgeon, institutional, regional, or national level, by means of qualifying aggregated data in reported literature (meta-analysis). Increasing transparency is required in healthcare outcomes and performance, which means that funnel plots will most likely play an increasingly important role as a quality control tool.


CONCLUSIONS
More widespread application of funnel plots in surgery will help to overcome some of the existing difficulties in assessing and reporting performance and identifying evidence-based information. The assessment and changes in future healthcare delivery could be partly influenced by further development of funnel plot methodology.
Mayer
Erik K
EK
Department of Biosurgery and Surgical Technology, Section of Surgical Quality and Epidemiology, Imperial College London, 10th Floor QEQM building, St Mary's Hospital, London, United Kingdom. e.mayer@imperial.ac.uk
Bottle
Alex
A
Rao
Christopher
C
Darzi
Ara W
AW
Athanasiou
Thanos
T
D004650:Employee Performance Appraisal; D013502:General Surgery / Q000592:standards*; D006801:Humans; D015233:Models, Statistical; D017063:Outcome Assessment, Health Care; D011785:Quality Assurance, Health Care; D011787:Quality of Health Care / Q000592:standards*; D013514:Surgical Procedures, Operative / Q000592:standards; D016896:Treatment Outcome