Oral Presentation 29th Australian and New Zealand Bone and Mineral Society Annual Scientific Meeting 2019

Ethnic differences in the incidence of atypical femur fractures in an Australian hospital setting (#53)

Hanh H Nguyen 1 2 , Amar Lakhani 1 , Cat Shore-Lorenti 2 , Roger Zebaze 2 , Amanda Vincent 1 3 , Frances Milat 1 2 4 , Peter R Ebeling 1 2
  1. Monash Health, Clayton, VIC, Australia
  2. Department of Medicine, School of Clinical Sciences, Monash University, Clayton
  3. Monash Centre for Health Research and Implementation, Monash University , Clayton, Victoria, Australia
  4. Hudson Institute of Medical Research, Clayton

Background: Atypical femur fractures (AFFs) are feared complications of antiresorptive drugs, and Asian ethnicity is a reported risk factor. We aimed to describe the ethnic differences in AFF incidence in an Australian hospital setting.

 

Methodology: Monash Health provides care to a culturally diverse population of 1.5 million. 204,358 individuals aged>50 years were admitted at Monash Health between 2009-2017. Admission and demographic data were extracted from electronic database. Ethnicity was defined by country of birth and language spoken, and coded according to ASCCEG1. Individuals with femur fractures were identified using ICD-10AM codes, and radiographic adjudication of subtrochanteric/femoral shaft (ST/FS) confirmed AFF cases. Cumulative incidence rate (per 100,000 person-years) for AFF and fracture groups were calculated and stratified by sex and ethnicity. Statistical analysis used Stata/IC 15.1.

 

Results: 97 AFFs (82 complete/15 incomplete) occurred in 71 individuals, of which 94% had antiresorptive exposure. Cumulative incidence rate of AFF cases was 4.2/100,000 person-years, lower than any ICD-10AM coded femur, NOF, pertrochanteric, and ST/FS fracture groups (204.6 /100,000 person-years; 131.0/100,000 person-years; 47.8/100,000 person-years; and 28.1/100,000 person-years, respectively). The age-adjusted relative risk for AFF was higher in females compared to males (Table 1). Asian ethnicity formed the highest proportion of AFF cases despite comprising a smaller proportion of the study population (32% vs 14%) and were 3.5 times more likely to sustain an AFF than non-Asian population (p>0.001) (Table 1). The incidence was highest in those from South East Asian countries (16.8/100,000 person-years). In contrast, Asians were not at increased risk of other femur fracture types. Australian born non-Indigenous individuals had a lower incidence of developing an AFF.

 

Conclusions: In an Australian hospital setting, the incidence of AFF is highest in those of Asian ethnicity. Further studies are required to elucidate the underlying mechanism, as this may provide clues to the pathogenesis of AFF.

 

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  1. Australian Standard Classification of Cultural and Ethnic Groups (ASCCEG), 2016. Retrieved from https://www.abs.gov.au/AUSSTATS/abs@.nsf/DetailsPage/1249.02016?OpenDocument