Bone Abstracts

Thalassemia (Thal) is a genetic disorder of hemoglobin synthesis. In its most severe form patients require chronic blood transfusions to sustain life leading to iron overload unless excess iron is removed by chelators. Deferasirox (DFX) and deferoxamine (DFO) are the two most common chelators. DFX has recently been shown to reduce osteoclast activity in vitro.

Objective: To explore the association between chelation therapy, bone density and vertebral fracture in a retrospective sample of patients with Thal.

Methods: Clinical charts were reviewed from patients with Thal who received care at UBCHO from 2001 to 2014. Abstracted variables included patient demographics, length of chelation, and iron burden. BMD scans were performed on one DXA (Hologic Discovery v12.6.1); full lateral spine scans were re-analyzed by one observer, and scored using the semi-quantitative assessment (Genant) for vertebral abnormalities (VA) and severity. Statistical analyses were performed using STATA, v9.2.

Results: 107 patients (22.8±11.4 years, 50% male) had on average 3.8 scans over 48.7 months. 52% of subjects were chelated with DFO, 27% with DFX, 8% with DFX+DFO (Combo), 13% no chelation therapy. On average, patients PA spine aBMD z-score was -2.4±1.1, hip aBMD z-score: −1.5±1.2, and whole body aBMD z-score: −2.5±1.0. Low bone mass (BMD z-score ≤−2.0) was more common in DFO and DSX (76, 72% respectively) than those not chelated (19% P=0.001). After controlling for age, gender, hypogonadism, time on chelation and age start chelation, there was a significant effect of chelation medications on PA aBMD (mixed effects linear model, P=0.002). Those subjects taking DFX had the highest BMD compared to DFO (adjusted 0.064 g/cm² higher, P=0.003). Time on chelation and hypogonadism were stronger predictors of hip BMD than chelator type. 61 patients had at least one VFA scan, of which 40% were abnormal. Incident VA were observed in 9 patients over an average of 6 years. No significant differences were observed in prevalence or number of VA by chelation group.

Conclusions: Results suggest that chelation with the oral drug DFX is associated with higher spine aBMD but not reduced VA in Thal. Further study is needed to determine the etiology of this potentially beneficial effect.

Disclosure: The authors declared no competing interests.