Hip fracture incidence and social deprivation: results from a French ecological study.

The association between socioeconomic status (SES) and hip fracture (HF) incidence was analyzed in France in 2008. In men and women, a decrease in HF incidence was observed as the social deprivation index increased. This result may be partly due to the protective effect of increasing body weight against HF.

INTRODUCTION: Regional variations in hip fracture (HF) incidence exist worldwide. Reasons for these variations remain unknown. As regional variations have also been observed for socioeconomic status, we analyzed the association between socioeconomic deprivation (SED) and HF incidence in France in 2008.

METHODS: From the French Hospital National Database, we selected all HF encoded as primary diagnosis in persons aged 30 years and over. The recently published French version of the European Deprivation Index (EDI) was used for SED analysis, and an EDI score was measured for the year 2007 in each French local municipality. The EDI score was categorized in quintiles. Poisson regression was performed to examine the association between HF incidence and EDI adjusted for age and sex. The population attributable fraction (PAF) was measured to calculate the proportion of excess cases of HF associated with social affluence.

RESULTS: In 2008, 83,538 HF were reported in France of which 59,143 were included in this study. Among them, 44,401 fractures occurred in women (75%) and 14,742 in men (25%). In both men and women, there was a decrease in the HF incidence with increasing SED index. In Poisson regression, the interaction of age class and sex was significant (p < 0.0001) and the EDI in quintiles was significantly associated with the incidence of HF (p < 0.0001). A higher number of people living in affluent residential areas corresponded to a higher risk of HF. The risk of HF is 2.42 times higher for those living in the most affluent group compared to those living in the most underprivileged group. The value of the PAF was calculated at 27.1%.

CONCLUSION: Social disparities in HF incidence exist in France with the most deprived municipalities having the lowest incidence. Prior knowledge demonstrates the strong relationships between body weight and HF risk as well as between body weight and the SED. The link found in our study between EDI and HF incidence as well as regional and temporal variations in HF incidence may be partly due to the protective effect of increased body weight against HF.