The increased risk of death associated with hip fractures was especially dramatic among younger women. In the 65- to 69-year-old age group, the odds of death were five times higher for women in a post-fracture year than they were for non-injured women of the same age, the study found.
Many of the 300,000 hip fractures that occur each year in the United States happen in postmenopausal women with the bone-thinning disease osteoporosis, typically after a fall or other accident. Researchers have already established that these fractures increase the risk of death, but they haven’t been able to rule out the possibility that women who fracture a hip are already at greater risk before their injury.
The new study, which carefully compared age-matched women with and without fractures, is the first to suggest a possible cause-and-effect relationship between hip fracture and death, says lead author Erin LeBlanc, MD, a researcher at Kaiser Permanente Northwest, a large nonprofit health plan in Portland, Ore.
“Before we might have assumed that sicker women are just more likely to get hip fractures,” she says. “But now we know that there is something about the hip fracture itself, and not an underlying condition, that is bringing on this increased risk of death.”
Dr. LeBlanc and her colleagues, whose findings appear in the Archives of Internal Medicine, tracked women in four states across the country between 1986 and 2005, as part of a larger study funded by the National Institutes of Health. From this pool of study participants, the researchers matched each of the 1,116 women who’d had hip fractures with four women of the same age who had not.
Overall, women who suffered a hip fracture had twice the odds of dying within one year of their injury than did their counterparts in the control group during the same year. Seventeen percent of the women who experienced a fracture died during the year, versus 8% in the control group. (In addition to matching the women by age, the researchers took into account body mass index, medical history, and several other risk factors for hip fracture.)
The top three causes of death—heart disease, stroke, and sepsis—were the same for both the fracture and control groups. But more than half of the deaths in the fracture group occurred within three months of the injury, and nearly three-quarters occurred within six months; this suggests that something about the surgery, hospital time, immobility, or rehabilitation required after a hip fracture makes women more vulnerable, says LeBlanc.
In an effort to separate out the effect of hip fractures from the underlying death risk associated with preexisting health problems, the researchers performed a more detailed analysis in women age 80 and up, a group that is generally sicker and more likely to die.
Hip fracture did not measurably increase the one-year odds of death in this age group as a whole, but it nearly tripled the odds among the subset of women who considered themselves to be in good or excellent health. The fact that hip fracture was linked to an increased risk of death only when illness was removed from the picture provides more evidence that fracture can be a cause of death, the researchers say.
Fractures appeared to be most dangerous in the youngest segment of study participants: For women 65 to 69, hip fracture quintupled the odds of death within one year. This was also the only age group in which the odds of death remained higher in the fracture group after the one-year mark.
The findings in these relatively young women should be a wake-up call to physicians and patients alike, says Silvina Levis, MD, director of the osteoporosis center at the University of Miami Miller School of Medicine.
“Many people assume that this increased mortality mostly applies to the very old,” says Levis, who was not involved in the study. “But having seen this result, I think younger women are the ones who should be very much aware and should talk to their doctors about ways of assessing risk.”
Women should have a bone-density test at age 65 (or younger if they have other osteoporosis risk factors), and those with low bone mass or osteoporosis may want to consider taking medications to reduce their risk of fractures, Levis says.
Dr. LeBlanc says it’s important for all postmenopausal women to get enough bone-strengthening calcium and vitamin D in their diet, avoid smoking and excessive alcohol intake, and assess their homes for hazards that could cause slips and falls. “Thinning of the bones is silent,” she says. “It doesn’t hurt, and if you’re not proactive you might not know you have it until you break something.”
These steps are especially important for a woman who has already had a fracture, Dr. LeBlanc adds, since she is at high risk for a second one.