Vivek Murthy, the US surgeon general, recently warned that “being socially disconnected” has a similar effect on mortality as smoking up to 15 cigarettes a day. This statement was widely reported in the media, including in the Washington Post, the Times and the Daily Mail. But where does this “15 cigarettes a day” figure come from?
Dr Murthy is referring to a study published in 2010 that explored social relationships and mortality rates. The researchers combined the data from 148 studies on the topic, in what is known as a “meta-analysis”, to arrive at a more robust statistical answer to their questions.
The meta-analysis contained data on 300,000 participants who were studied for an average of seven and a half years. The researchers explored the extent to which social relationships can influence the risk of premature death, the aspects of social relationships that are most likely to predict an early death, and any factors that mitigate the risk.
