SCIENTIFIC LETTER The risk model of choice for coronary surgery in the UK

Coronary bypass surgery is perhaps the most investigatedsurgical procedure1 with clear end points for outcomesuch as operative mortality. Consequently, it has long been regarded as a sentinel operation for outcome.2 3 Over 25 000 coronary bypass operations are performed per year in the UK and the operative mortality has reached a plateau in recent years of approximately 3%. The risk that an individual patient will not survive surgery depends on many factors, some of which can be quantified and form the basis of risk scoring systems. Several risk stratification systems have developed over recent years with varying complexity, including those based on simple additive models such as Parsonnet,4 EuroSCORE5–7 and others.8 9 More complex statistical algorithms using logis-tic regression10 11 and Bayes modelling8 also exist. The ideal model should have high predictive accuracy (ability to predict the proportion of patients who will have an adverse outcome), good discriminatory power (ability to identify which patients are likely to have an adverse outcome), as well as being simple and user-friendly. The aim of this study was to determine the most suitable risk model for coronary bypass surgery in the UK by testing five models on the National Adult Cardiac Sur-gical Database. PATIENTS AND METHODS Data from 16 619 patients who underwent coronary bypass surgery were obtained from the UK National Adult Cardiac Surgical Database.12 All cardiothoracic centres in the UK are invited to contribute data from their local systems to this database that is run on a central server using the Patien