FRAX-based fracture probabilities in South Africa

Helena Johansson,Sapna S Dela,Susan L Brown,Eugene V Mccloskey,Mattias Lorentzon,Liesbeth Vandenput,Mkhululi Lukhele,Magda Conradie,Nicholas C Harvey,Farhanah Paruk,Enwu Liu,John A Kanis,Asgar A Kalla,Pariva Chutterpaul,Johannes D Jordaan,Ozayr Mohamed,Bilkish Cassim

doi:10.1007/s11657-021-00905-w

Abstract

SummaryThe hip fracture rates in South Africa were used to create ethnic-specific FRAX® models to facilitate fracture risk assessment.IntroductionThe aim of this study was to develop FRAX models to compute the 10-year probability of hip fracture and major osteoporotic fracture and assess their potential clinical application.MethodsAge- and sex-specific incidence of hip fracture and national mortality rates were incorporated into a FRAX model for the White, Black African, Coloured and Indian population of South Africa. Age-specific 10-year probabilities of a major osteoporotic fracture were calculated in women to determine fracture probabilities at a femoral neck T score of -2.5 SD, or those equivalent to a woman with a prior fragility fracture. Fracture probabilities were compared with those from selected countries.ResultsProbabilities were consistently higher in Indian than in Coloured men and women, in turn, higher than in Black South Africans. For White South Africans, probabilities were lower than in Indians at young ages up to the age of about 80 years. When a BMD T score of −2.5 SD was used as an intervention threshold, FRAX probabilities in women age 50 years were approximately 2-fold higher than in women of the same age but with an average BMD and no risk factors. The increment in risk associated with the BMD threshold decreased progressively with age such that, at the age of 80 years or more, a T score of −2.5 SD was no longer a risk factor. Probabilities equivalent to women with a previous fracture rose with age and identified women at increased risk at all ages.ConclusionsThese FRAX models should enhance accuracy of determining fracture probability amongst the South African population and help guide decisions about treatment.

Highlights

Osteoporosis is a common, chronic and costly condition; its clinical consequence is fracture that in turn is a major cause of disability and death [1]
80% of South Africans are of African ancestry (Black) and the remaining population comprises mainly European (White), Indian and multiracial ancestry (Coloured)
Probabilities were consistently higher in Indian than in Coloured men and women, in turn, higher than in Black South Africans

Summary

Introduction

Osteoporosis is a common, chronic and costly condition; its clinical consequence is fracture that in turn is a major cause of disability and death [1]. Disability due to osteoporosis is greater than that caused by any single cancer, with the exception of lung cancer and comparable or greater than that lost to a variety of chronic noncommunicable diseases, such as rheumatoid arthritis, asthma and high blood pressure-related heart disease [2, 3]. A wide variety of treatments is available that favourably affect bone mass and thereby decrease the risk of fractures associated with osteoporosis [4]. The use of such interventions by health care practitioners is assisted by instruments that assess patients’ fracture risk to optimise clinical decisions about prevention and treatment. FRAX models are available for 73 countries in 2020 covering more than 80% of the world population at risk [7] and have been incorporated into more than 100 guidelines worldwide [8]

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