Drop in hip fracture risk tied to lifestyle factors

A decrease in hip fractures among adults born more recently may be due to improved lifestyle factors such as reduced smoking and less heavy drinking, according to a study published in 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,” Timothy Bhattacharyya, MD, head of Clinical and the Investigative Orthopaedic Surgery Section and a contractor in the Office of Clinical Director at the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), told Healio Primary Care.

He added that the study is a reminder “that reducing smoking and heavy drinking, especially among young people, improves their bone health and lowers the risk of a disabling hip fracture.”

Bhattacharyya and colleagues conducted a population-based cohort study of 10,552 participants from the Framingham Heart study. Participants were followed prospectively for first hip fracture from January 1970 through December 2010.

During follow-up, the researchers evaluated the incidence of hip fracture and the prevalence of risk factors for hip fractures.

The study included more than 105,000 person-years among participants, with a shift toward offspring participants during the 1980s and 1990s.

After adjusting for age, Bhattacharyya and colleagues found from 1970 to 2010, the incidence of hip fracture decreased by 4.4% per year (95% CI, 6.8-1.9).

They determined that both period and birth cohort associations were statistically significant. For instance, they noted that the incidence of hip fracture was 759 per 100,000 person years for those aged 85 to 89 years in the offspring group, compared with 2,018 per 100,000 person years in the original cohort.

Bhattacharyya and colleagues noted that the decrease in hip fractures coincided with a decrease in smoking — from 38% in the 1970s to 15% in the late 2000s — and a decrease in heavy drinking, from 7% in the 1970s to 4.5% in the late 2000s.

Other risk factors for hip fractures, including being underweight (BMI under 18.5), obesity (BMI over 30) and menopause before the age of 45 years, remained stable throughout the study period.

When examining participants who never smoked, the researchers found that their incidence of hip fracture decreased by 3.2% (95% CI, 60.4) per year.

The difference in the decrease of the entire population and nonsmokers — 1.5% per year — was similar to the hazard ratio created by smoking (1.5; 95% CI, 1.14-1.96).

“We saw a strong time-period effect,” Bhattacharyya said. “People who were born later simply have a lower risk of hip fracture than the people who were born in the ’40s and ’50s.”

He said this is likely due to a combination of factors, including better nutrition, more active lifestyle and less smoking compared with people in earlier years.

“It’s good news: you are at a lower risk of a hip fracture than your parents were, even after adjusting for age,” Bhattacharyya said.