Summary

The aim of this study was to estimate the incidence of hip fracture in Zanjan, Iran and to describe its seasonal variation. A total of 244 cases of hip fractures (131 men, 113 women) were recorded during 1 year. The annual age-standardized incidence rates were 206.5 and 214.8 per 100,000 men and women, respectively. Most fractures occurred in winter, in-house and daytime. In-hospital mortality was 2.5%. Incidence rate of hip fracture (HF) was less than in western countries mostly due to lower incidence in women, which is probably because of breast-feeding.

Introduction

One of the most important consequences of osteoporosis is HF, which causes high mortality, morbidity, and significant costs. The incidence of HF in the elderly varies in different areas. Various incidence rates of HF have been reported from countries in the Middle East. The aim of this prospective study was to estimate the annual incidence of hip fracture in Zanjan, a province of Iran, and to describe the seasonal variation of HF incidence which has not been evaluated in two previous studies conducted in this country.

Materials and methods

All cases of HF aged 50 years or more admitted in three referral hospitals with orthopedics facilities in Zanjan province between 21 March 2006 and 20 March 2007 were subjected in the study. The age- and sex-specific incidence rates of hip fracture per 100,000 person-years were calculated using the population data from the last national census in Iran 2007.

Results

A total of 244 cases of hip fractures (131 men, 113 women) were recorded. The annual age-standardized incidence rate was 214.8 per 100,000 women and 206.5 per 100,000 men. The number (%) of fall-induced HF was 88 (67.2%) in men and 102 (90.3%) in women. The female to male ratio for total and fall-related HF was 1.0 and 1.1, respectively. The HF was more predominant in winter (38.5%). In-hospital mortality was 2.5%, and majority of HF were sustained in-house and daytime.

Conclusion

We found a relatively low incidence of hip fracture and fall-related hip fracture in Iran than those in western countries, which is mostly due to the lower rate in women. These findings disagree with our expectations considering the bone mineral density and vitamin D status of Iranian population, especially women. Breastfeeding could be one of the probable protective factors.