Every Christmas season, heart-related deaths spike in the U.S.
Among researchers, the question of cause has always been up in the air. On the one hand, the holidays are associated with strenuous schedules and travel, rich meals, increased alcohol consumption and extra emotional stress ― all risk factors for heart issues. On the other, the event coincides with winter temperatures, which are known to restrict blood vessels, putting extra strain on the heart.
A new study published in the Journal of the American Heart Association lays blame at the feet of Father Christmas, not colder temperatures, thanks to a perfect comparison group: New Zealanders, a culturally similar population that celebrates Christmas during their summer time.
New Zealand is located in the Southern Hemisphere, so people in this country experience their summer weather from December through February. But since they too were once English colonies, New Zealanders celebrate the lead-up to Dec. 25 with feasting, merrymaking, travel and parties, just like Americans do.
Researchers from the University of Melbourne in Australia (another “upside-down Christmas” country) wanted to see if Kiwis also experience a spike in heart attacks during the holidays, even though they were celebrating it during the hottest months of their year.
They analyzed New Zealand death data from 1988 to 2013 and came up with an “expected” number of deaths for each day of the year. Then they compared their model to the actual deaths each day over the Christmas holiday period, defined as Dec. 25 through Jan. 7. They found a 4 percent increase of cardiac events over the period, leading to about four additional deaths each year.
They also found that people who died during this holiday season tended to be, on average, about one year younger than those who die of similar causes during the rest of the year.
The recent study results align with a 2004 statistical analysis that tried to separate the effect of the Christmas holiday from wintertime on natural causes in America. It estimated that the U.S. experiences an almost five percent higher rate of cardiac deaths during the Christmas and New Year’s holiday season, as well as other deaths from natural causes.
This is now the third time the Christmas cardiac death effect has been measured in a different part of the world. In addition to the U.S. and New Zealand, British researchers also published similar analyses on deaths in England in 2005 and found that while there is no cardiac death spike on Christmas Day, there is one on New Year’s day. England, like the U.S., celebrates Christmas during wintertime.
The Australian researchers aren’t sure what caused this spike of cardiac deaths in New Zealand during the Christmas season, but previous research best supports two possible explanations. The first is that the holidays prevent people from seeking medical care when they normally would, due to travel and a lack of familiarity with new surroundings. The second theory is about “displacement of death” through sheer will — that people would actually either try to delay death or speed it up in consideration of a holiday date that is special to them.
“The ability of individuals to modify their date of death based on dates of significance has been both confirmed and refuted in other studies, however it remains a possible explanation for this holiday effect,” said lead author Josh Knight of the Centre for Health Policy at the University of Melbourne in a statement about the study.
Other potential theories for the spike in heart-related deaths in New Zealand include the holiday’s effect on diet, alcohol consumption and stress, although more research is needed to measure these potential effects.
If you’re traveling for the holiday season, do some extra research on your destination to see which clinics and hospitals you should visit in case you experience any unexpected medical events.