A recent article by Wilson and colleagues1 proposes the mandatory ECG screening of athletes as a means of reducing the risk of sudden cardiac death in this population. The idea of such screening originated with the studies of Dr Corrado and his colleagues in Italy.2 The concept has subsequently received support from several European groups, Dr Corrado being involved in some of these: the International Olympic Committee Medical Commission,3 the European Society of Cardiology4 and the Féderation Internationale de Football Association (FIFA).5

A proper starting point for a consideration of this issue is Bayes’ theorem. This theorem makes clear that mass screening cannot be effective and will inevitably lead to a high proportion of false positive results if one is using a fallible test procedure when attempting to detect a rare risk. Wilson and associates1 attempted to increase the frequency of their positive outcomes by assessing the frequency with which their ECGs detected certain “abnormalities” such as the Wolff–Parkinson–White (WPW) syndrome, thought to be associated with an increased risk of sudden death. One …