TY - JOUR T1 - How to prove without randomised controlled trials that automated external defibrillators used by the public save lives? JF - Heart JO - Heart DO - 10.1136/heartjnl-2018-313071 SP - heartjnl-2018-313071 AU - Paul A Calle AU - Nicolas Mpotos Y1 - 2018/03/07 UR - http://heart.bmj.com/content/early/2018/03/08/heartjnl-2018-313071.abstract N2 - In their Heart manuscript, Aschieri et al report an impressive impact of the availability of automated external defibrillators (AEDs) on survival after sudden cardiac arrest (SCA) in amateur sports centres.1 For this observational study, the authors analysed data from a registry on all out-of-hospital SCA cases from the Piacenza area (Italy). Using the predetermined variable ‘location’, they selected 26 cases. As AEDs were gradually introduced over an 18-year period, a comparison could be made according to the on-site presence of an AED. Neurologically intact survival rates in sports centres with and without on-site AED were 93% (14/15) and 9% (1/11), respectively.At first glance, this impressive difference should lead to patently clear conclusions. A closer look at the methodology and the data, however, urges caution as at least four (often interrelated) issues potentially leading to bias should be mentioned. First, the AEDs were not allocated at random since the sports centres decided whether or not to start a local AED project, implying that all results are prone to bias. Second, the time of collapse was not registered. Although the authors state that all cases were witnessed and that the emergency medical services (EMS) dispatch centre was never alerted for pre-arrest symptoms, one cannot exclude that in sports centres with an on-site AED the collapse to call interval was shorter, for example, because a local campaign aiming at an optimal AED use also emphasised the importance of an early call to the dispatch centre. Third, the gradual introduction of AEDs (ie, only 36 devices in 2007 vs 207 in 2016) is reflected by an increasing proportion of SCA cases in AED-equipped sites (ie, only 1 out of 8 cases between 1999 and 2007 vs 14 out of 18 between 2008 and 2016). … ER -