Does a lack of first aid skills kill as many people as cancer?

Last night, nine million people watched a man choke to death.   In one of the commercial breaks during the first episode of ITV1's new series of Downton Abbey, the channel broadcast an advert containing a claim that may have shocked its primetime audience.   The advert was from first aid charity St John Ambulance, and it placed us in the middle of a story: a middle-aged man is diagnosed with cancer, undergoes treatment and begins to recover his health, only to die suddenly after choking to death at a neighbourhood barbeque.   As friends and family cluster around him and his young daughter looks on, St John Ambulance hit us with a startling statistic: "First aid could help prevent up to 140,000 deaths every year. The same number of people that die from cancer."   The scenario is fictional, but are the statistics telling the truth?   For a start, how do we know that 'First aid could help prevent up to 140,000 deaths every year'?    St John Ambulance calculated the 140,000 figure by analysing data from the Office for National Statistics (ONS), which collates information on UK mortality rates.   According to their website, first aid can be useful in the following situations: choking, heart attack, severe bleeding, dealing with an unconscious person, and dealing with someone who isn't breathing.   The Red Cross and the NHS also consider first aid to be helpful for the same medical emergencies. So we're not just talking about the first aid you'd administer to a cut or a first-degree burn, but the kind of medical assistance that's vital before an ambulance arrives.    So can we know that 140,000 of these cases lead to deaths every year?   We got in touch with St John Ambulance to ask how they calculated the striking statistic. They informed us that their medical experts analysed the ONS data set for UK death registrations in 2010: for every single cause of death recorded in the mortality data, their medical experts made a judgement about whether or not first aid could've prevented a fatality. Yet questions remain.   If, by way of example, 5,000 people died of a heart attack in a given year, would St John Ambulance suggest that 5,000 individuals might have survived if there had been a first-aider to hand? Or did they calculate a probability - that a certain proportion of the 5,000 might have been saved? Whatever the logic, we need to be shown how they arrived at their final figure of 140,000.   When we look at the other side of the comparison - the implied claim that 140,000 people die from cancer each year - we find ourselves on firmer statistical ground. The ONS does record the number of deaths attributed to cancer every year: in 2010, 141,446 people died from the disease.   Until we receive a full breakdown from St John Ambulance, we can't assess how rigorous their comparison is. While their cause might be noble, it is nevertheless important that people can have faith in the numbers reported by St John Ambulance. If the data isn't available to back up a claim, this isn't possible.   It's for this reason that the Advertising Standards Agency (ASA) requires that statistical claims be 'objectively substantiated'. This isn't simply to prevent the scale of the problem from being exaggerated. It's also vital that viewers are able to trace the figures if they so wish.   Yesterday's broadcast reached as many as nine million people. We'd like to think that gives St John Ambulance nine million reasons to show their working.   Update (04/07/2013): We've taken this case to the Advertising Standards Authority. To read our thoughts on its verdict, please click here.   Flickr image courtesy of mac_ivan