Prevalence and risk factors of fractures in transfusion dependent thalassemia - A Hong Kong Chinese population cohort.

ABSTRACT

OBJECTIVE: To delineate the prevalence and associated risk factors of low BMD, osteoporosis/bone fragility and fracture in transfusion-dependent thalassemia (TDT) in the Chinese population in Hong Kong. DESIGN, PATIENTS AND MEASUREMENTS A retrospective cohort study design was employed. Patients of TDT who had serial Hologic dual-energy X-ray absorptiometry (DXA) from 2010 to 2016 and received regular transfusion for at least 5 years were recruited. Clinical and biochemical data, from 5 years before the first DXA scan, were retrieved from the electronic record system of the Hospital Authority, till 30 June 2020. Low bone mineral density and osteoporosis/bone fragility are defined by the ISCD 2019 position guidelines. RESULTS: Seventy-seven patients were included in the analysis. The fracture prevalence of TDT among the Chinese population in Hong Kong was 15.58%. Up to 55.84% of patients had low bone mineral density, and 5.19% patients had osteoporosis/bone fragility state. The median age at first fracture was 31.73 years (range 24.06-44.18 years). In the regression analysis, a higher log(10) transformation of average ferritin levels over 5 years before the first DXA scan was significantly associated with fracture occurrence regardless of bisphosphonate treatment (OR 310.73, 95% CI 3.99-24183.89, p = .010). Mean average ferritin level over 5 years was 6695.5 ± 2365.7 pmol/L (fracture group) versus 4350.7 ± 3103.2 pmol/L (non-fracture group), p = .016. Hip and spine BMD Z-score did not have statistically significant association with fracture occurrence. CONCLUSION: Iron overloading plays an important role in adverse bone health in TDT. Dual X-ray densitometry is insufficient in predicting fracture risk.