LAUSR

Background Hip fractures are a societal burden because of their high related morbidity and mortality, and the cost they generate. With the ageing of the population, worries grow about an increase of the incidence and incidence rate of hip fracture in the next years. Numerous studies have shown an increase in the incidence whilst a decrease in the incidence rates of hip fracture in the majority of Europe countries and North America. These data come from heterogeneous studies regarding the reference population used, and thus their interpretations remain controversial. Objectives The aim of our study was to assess the impact of the choice of the reference population in the interpretation of incidence rates data, using country-based data of French population. Methods We used data related to the hospitalizations for hip fracture in France between 2002 and 2013 in patients over 59 years, extracted from the French National Hospital Database. Data were based on the whole French population and were classified by sex and age (60–74, 75–84, over 84 years, over 59 years). We first calculated the crude incidence rates of hip fracture by dividing the number of hospitalizations for hip fracture by the corresponding populations. To assess the impact of the choice of the reference population, we then calculated the crude and adjusted incidence rates using direct standardisation on age with three different reference populations (2002, 2013, mean population of 2002–2013). Results Between 2002 and 2013 in France, the incidence of hip fracture raised of 4.8% in women (from 49 287 to 51,661) and 21.8% in men (from 12 716 to 15,482), aged 59 years and over. In the meantime, French population over 59 years increased more with a rise of 21.3% in women and 28.7% in men, which explained a decrease in the crude incidence rates of 13.6% in women and 5.4% in men. However, this decrease was even more obvious after direct standardisation whatever population of reference was used in women: 24.9%, 25.6% and 26.1% and men 18.2%, 19.2%, 19.8% with respectively 2002, 20013, and 2002–2013 as population of reference. Conclusions The incidence rates of hip fracture decreased in France between 2002 and 2013 in men and women aged 60 years and over. The decrease is more important after direct standardisation whatever population used as a reference as a results of a difference in age-structure of the population that can be erased by the process of direct standardisation. In conclusion, the incidence of hip fractures continues to grow despite a reduced incidence rate throughout a 12 year-period. References [1] Center JR, Mortality after all major types of osteoporotic fracture in men and women: An observational study. Lancet1999. [2] Vestergaard P, Increased mortality in patients with a hip fracture-effect of pre-morbid conditions and post-fracture complications, Osteoporos Int2007. [3] Bliuc D, Mortality Risk Associated With Low-Trauma Osteoporotic Fracture and Subsequent Fracture in Men and Women, JAMA2009. [4] Cummings SR, Epidemiology and outcomes of osteoporotic fractures. Lancet2002. [5] Gullberg B, World-wide projections for hip fracture. Osteoporos Int1997. [6] Briot K, Changes in number and incidence of hip fractures over 12 years in France, Bone2015. [7] Ballane G, Secular trends in hip fractures worldwide: opposing trends East versus West, J Bone Miner Res2014. Disclosure of Interest None declared