MONDAY, Dec. 13 (HealthDayNews) -- Researchers have some sobering news during this festive season: Americans are more likely to die on Christmas Day, the day after Christmas, and on New Year's Day than on any other day of the year.
In a comprehensive study of 53 million U.S. death certificates spanning the years 1973-2001, researchers discovered significant spikes in both cardiac and non-cardiac deaths during the holidays.
They also warned this trend is on the rise.
"From the point of view of a public health problem, it's something that's getting worse over time rather than better," said lead researcher David Phillips, a professor of sociology at the University of California at San Diego.
He believes the phenomenon may stem from patients' tendency to postpone medical care during the holidays, as well as holiday-specific staffing patterns at hospitals nationwide.
The findings appear in the Dec. 14 issue of Circulation.
In 1999, a study led by Dr. Robert A. Kloner of the University of Southern California in Los Angeles found death rates jumped by about a third in December and January compared to those seen in the summer months.
However, the study looked only at deaths occurring over a 12-year period in and around Los Angeles. Phillips's study is much broader than that.
"We were the first to look at this phenomenon using all death certificates from the entire country" over a longer time span, Phillips explained. This enormous statistical power enabled the researchers to identify patterns in mortality for every day of the year.
They found that three days -- Dec. 25 and 26, and Jan. 1 -- were the worst in terms of deaths from both cardiac and non-cardiac causes.
"In the case of heart deaths, there's an 11.9 percent excess [of deaths] on those days" beyond what would normally be expected during that season, Phillips said.
"In the case of the non-heart deaths for those three days, what you find is an extra 12.2 percent of deaths," he added.
The observed spikes in death rates were especially sharp among individuals who died soon after onset of their symptoms -- patients who were dead on arrival (DOA) by the time they reached emergency care. During the holidays, DOA rates climbed by nearly 5 percent over normal, the researchers found.
Why the sharp rise in deaths around the holidays? According to Phillips, a close examination of data ruled out likely suspects such as cold weather or changes in diet and exercise patterns. For example, he said, the rise in holiday deaths was seen even among nursing home patients, whose diets and activities tend to be strictly controlled.
Kloner suggested that the emotional stress associated with the holiday season might be to blame -- things like "dealing with relatives whether you like them or not, financial stresses, and travel during the holidays."
But Phillips disagreed. He pointed out that the Christmas and New Year's Day peaks in mortality were also seen among individuals affected by advanced Alzheimer's disease. "Many of these people don't even understand anymore that there is a holiday going on," he said. Based on that finding, "we don't think the evidence points neatly toward the idea of emotional stress playing a role," Phillips said.
Instead, two factors -- patient attitudes to symptoms and hospital staffing changes -- appear most likely to blame, he said.
According to Phillips, too many patients adopt an "'I'll take care of that later'" attitude when presented with unsettling symptoms during the holidays.
"They underuse urgent-care facilities. That's been shown in previous studies," he said. There's also the added complication of holiday travel. According to Phillips, individuals far away from their doctors may choose to put off needed care until their return.
Holiday staffing patterns at hospitals may play a key role, as well. "It could be there's reduced levels of health-care staffing, or staff members who are unfamiliar with individual patients," Kloner said.
According to Phillips, more study needs to be done to see if better hospital staffing practices can reduce the holiday rise in mortality.
The findings are much more than a minor statistical bump, he said. According to the study, the "holiday effect" may account for an additional 42,039 U.S. deaths over the study period.
And it's a trend that's been growing in significance year by year, the researchers add. According to the study, the first three years of data (1973-1975) pegged excess holiday mortality at just 0.95 percent above what would be expected during the winter months. By the study's end, 1999-2001, that bump had risen nearly fivefold, to 4.4 percent above seasonal norms.
"This effect is getting bigger over time," Phillips said. "It seems risky to ignore it."
To learn more about the warning sings of heart attack and stroke, visit the American Heart Association.