Fewer people are fracturing their hips in the United States and other high-income countries than three decades ago, and the reason has more to do with improved lifestyles, especially reduced smoking and less heavy drinking, than with new drug treatments, according to a study published this week in the JAMA Internal Medicine.
“Promoting a healthy lifestyle over the past 30 years is a key reason that we are seeing less hip fractures each year,” said Dr. Timothy Bhattacharyya, the study’s senior author and a researcher at the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), in an interview with Healio.com reporter Erin Michael.
The study also underscores the message that “reducing smoking and heavy drinking, especially among young people, improves their bone health and lowers the risk of a disabling hip fracture,” he added.
The chances of breaking a hip increase as you age. In the United States, about 300,000 people aged 65 and older are hospitalized for hip fractures each year, according to the Centers for Disease Control and Prevention (CDC). Three quarters of those fractures are in women, and almost all (95 percent) involve falls.
A hip fracture can lead to medical complications, such as blood clots, infections and pneumonia. One in five older adults who break a hip die within a year of the injury. Hip fractures can also greatly affect quality of life, making it impossible for people to regain their previous levels of physical functioning.
For the study, Bhattacharyya and his colleagues used data collected from 5,634 women and 4,918 men who participated in the long-running Framingham Heart Study, which started in 1948 and is now on its third generation of participants. Although the study was launched to better understand the risk factors for heart disease, its data has been mined for factors that contribute to many other medical conditions, including hip fractures.
The current study identified all of the 10,552 participants who had a first hip fracture between 1970 and 2010. They then looked to see which risk factors for hip fractures (ones that doctors use to determine if a patient needs preventive medical treatment) were most common among them.
The researchers found that the incidence of hip fractures decreased significantly — by 4.4 percent per year — during the 40 years of the study. That decrease occurred in both men and women.
For example, when the study’s oldest cohort (those who enrolled in the study between 1948 and 1952) were aged 85 to 89, they were about 2.5 times more likely to have fractured their hip than the study’s “offspring” cohort (those who enrolled beginning in 1971) when they reached the same age.
Explaining the decrease
The researchers determined that the decline in hip fractures could not be explained by better methods of diagnosis and treatment. The incidence of such fractures began dropping in 1975. That was 15 years before at least 10 percent of older women were taking estrogen replacement therapy to protect against osteoporosis and 20 years before bisphosphonates (which are also used to slow down bone thinning) came into use.
In the best-case scenario, say the study’s authors, the use of bisphosphonates has cut the rate of hip fracture 4.8 percent in total since 1995.
The researchers then turned their attention to risk factors. They found that most risk factors for hip fractures, such as being underweight or experiencing early menopause, had remained stable over the study period. But two hadn’t. The proportion of people who smoked dropped from 38 percent to 15 percent, and the proportion who drank heavily (three or more drinks per day) decreased from 7 percent to 4.5 percent.
Those two risk factors explain at least some of the decline in hip fractures in recent decades, the researchers conclude.
“While there is still a need to treat patients with osteoporosis, health care providers should continue to encourage public health interventions, specifically smoking cessation and preventing heavy drinking of alcohol,” says Dr. Douglas Kiel, one of the study’s authors and senior scientist at the Hinda and Arthur Marcus Institute for Aging Research, in a released statement.
A long look back
The participants in the Framingham study are all white and have a lower rate of obesity than the U.S. national average. The study’s findings may not be generalizable, therefore, to other populations. In addition, the study did not include bone density measurements, as such testing was not available before the 1990s.
Still, as the study’s authors point out, the Framingham Heart Study data allowed them “to look further back in time than previous studies,” a factor that adds weight to the findings.
Less smoking and drinking may not be the only lifestyle-related reasons the second generation of Framingham participants were less likely to fracture a hip. The current study didn’t look at physical activity, but more active lifestyles may also be behind the lower incidence in hip fractures. As I reported in Second Opinion last year, researchers have found that older women who remain physically active — even if that activity involves taking relatively slow daily walks — are less likely to fall and fracture a hip.
FMI: You’ll find an abstract of the study on the JAMA Internal Medicine website, but the full study is behind a paywall.