Sven Drefahl's research is based on Danish register data, and these findings were first published in 2010. Since then, he has made progress at why women with older husbands die earlier. As stated in the Guardian:

"He’s been looking at causes of death. The answer is that these women are far more likely to die of “external causes” than other married women – that is, they are more likely to die of accidents that are not suicides."

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