Epidemiology of hip fracture in Iran: results from the Iranian Multicenter Study on Accidental Injuries

The incidence of hip fracture varies substantially between countries. As a result of improving life expectancy, the number of elderly people susceptible to hip fractures is increasing rapidly in the developing world. Little is known, however, about the epidemiology of hip fractures in the Middle Eastern countries. In this study, our objective was to estimate the incidence of hip fracture in Iran and compare it with other populations.

The data used were obtained from the Iranian Multicenter Study on Accidental Injuries, a large-scale population-based study conducted in nine provinces across the country. All of the hospitals in these provinces, which provide services to about 9.5 million people, were prospectively surveyed for any incident injury resulting from accidental events occurring in the study period of 135 days (4.5 months). All patients aged ≥50 with radiographically confirmed proximal femur fractures were included in this study. A total of 555 new cases of hip fracture (284 male, 271 female) were recorded during the study period. The annual incidence of hip fracture per 100,000 person-years was 115.2 (95% CI: 107.2–123.7) in men and 115.6 (95% CI: 107.4–124.3) in women; of these,73.2 and 89.2%, respectively, were fall-related fractures. The female-to-male ratios for fall-induced and total hip fracture rates were 1.2 and 1.0, respectively.

The incidence rates increased exponentially after the age of 60 years in both genders and nearly tripled with each successive decade. When these results are compared to those of other studies, the Iranian age-standardized incidence rates of 127.3 (men) and 164.6 (women) per 100,000 person-years are considerably lower than those of all Western countries when standardized to data on the U.S. population in 2000. When compared with incidence rates reported for other Asian countries, those of Iranian females are the lowest next to China.

The low incidence rate of hip fracture for older Iranian women may be the result of several potential factors related to genetic or lifestyle differences between Iranians and people of other countries. Further studies are required to investigate contributing factors in more detail.