Elderly men and women face an increased risk of death after a spouse’s hospitalization, a study of more than 1 million people shows.

“People are interconnected, and their health is interconnected,” Dr. Nicholas A. Christakis of Harvard Medical School in Boston, one of the study’s authors, told Reuters Health.

While the so-called bereavement effect, in which a person is more likely to die after a spouse’s death, is well-documented, less is known about what happens to a person when a wife or husband is ill, Christakis and Dr. Paul D. Allison of the University of Pennsylvania in Philadelphia note in this week’s issue of The New England Journal of Medicine.

To investigate, they looked at 518,240 couples enrolled in Medicare in 1993, following them for nine years. During that time, 74 percent of the men and 67 percent of the women were hospitalized at least once, while 49 percent of husbands and 30 percent of wives died.

Overall, men were at a 22 percent increased risk of death after a spouse’s hospitalization, while a husband’s hospitalization increased a woman’s mortality risk by 16 percent.

For both sexes, overall mortality over the nine-year period was about a quarter of what it would have been after a spouse’s death. But when the researchers looked at just the first 30 days after hospitalization, mortality was much greater - nearly as high as if the husband or wife had died.

This is probably due to the immediate effects of stress, according to Christakis; for example, during those first 30 days after the shock of a spouse’s hospitalization people may be more likely to have heart attacks, get in car accidents, or even drink to excess.

Mortality risk declined after 30 days, but remained higher than normal and climbed again towards the end of the nine-year period. This likely reflects the long-term demands of caring for and supporting a partner who is less and less able to provide support in return, Christakis says.

The researchers also found that a person’s mortality risk varied depending on the reason why a spouse was hospitalized. The greatest danger of death was seen for the most incapacitating illness; hospitalization for dementia, psychiatric illness, and hip fracture all conferred a greater risk of spousal mortality than colon cancer or lung cancer, for example.

“Anything that’s really physically or mentally disabling, quite apart from whether it kills you, it’s harmful for your partner,” Christakis said.

Policymakers, insurers and others concerned with large-scale health care costs should be aware that by providing care for a person, they could be helping to save his or her partner’s life as well, he added.

SOURCE: The New England Journal of Medicine, February 16, 2006.