Transfusion-dependent patients typically develop iron-induced cardiomyopathy, liver disease, and endocrine complications. We aimed to estimate the incidence of endocrine disorders in transfusion-dependent thalassemia (TDT) patients during long-term iron-chelation therapy with deferasirox (DFX).We developed a multicentre follow-up study of 426 TDT patients treated with once-daily DFX for a median duration of 8 years, up to 18.5 years. At baseline, 118, 121, and 187 patients had 0, 1, or ≥2 endocrine diseases respectively. 104 additional endocrine diseases were developed during the follow-up. The overall risk of developing a new endocrine complication within 5 years was 9.7% (95%CI=6.3–13.1). Multiple Cox regression analysis identified 3 key predictors: age showed a positive log-linear effect (adjusted HR for 50% increase=1.2, 95%CI=1.1–1.3, P=0.005), the serum concentration of thyrotropin (TSH) showed a positive linear effect (adjusted HR for 1 mIU/L increase=1.3, 95%CI=1.1–1.4, P<0.001) regardless the kind of disease incident, while the number of previous endocrine diseases showed a negative linear effect: the more the diseases at baseline the less the chance of developing a new one (adjusted HR for unit increase=0.5, 95%CI=0.4–0.7, P<0.001). Age and TSH had similar effect sizes across categories of baseline diseases. Adding levothyroxine administration as a covariate, the estimates did not change. Although in DFX-treated TDT patients the risk of developing an endocrine complication is generally lower than the previously reported risk, there is considerable risk variation and the burden of these complications remains high. We developed a simple risk score chart enabling clinicians to estimate their patients’ risk. Future research will look at increasing the amount of variation explained from our model and testing further clinical and laboratory predictors, including the assessment of direct endocrine MRI.
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