Clinical Effectiveness of Iron Chelation Therapies in Syrian Patients with β Thalassemia Major: Suboptimal Clinical Outcomes and High Prevalence of Iron Overload

Thalassemia is the most prevalent autosomal abnormality in the population of Syria. In 2013, the total number of registered thalassemia patients is 8300. Disease prevalence is reinforced by the high rate of consanguineous marriages especially in the rural regions of this Middle Eastern and Mediterraneancountry. Regular blood transfusions and iron chelation therapy (ICT) have significantly improved survival and reduced morbidity of patients withβ thalassemia major (BTM). Although ICTs are provided free of charge by the government to all (BTM) patients, adequate monitoring of therapeutic outcomes is lacking, and cardiac complications still represent significant morbidity and remain the leading cause of mortality.

This study aimed at evaluating the prevalence of poor chelation in Syrian patients with BTM, and assessing the effectiveness of different iron chelation regimens provided by the National Thalassemia Program.

We conducted a single-centered study encompassing two phases; i) a retrospective chart review of serum ferritin levels of all female and male patients (≥ 3y) with (BTM) receiving iron chelation regimens (mono- or combination therapy) in 2009 and 2010; and ii) a 15 month prospective observational study to evaluate the effectiveness of desferrioxamine (DFO) monotherapy (at a dose of 40-50 mg/kg given over 8–10 h on 5-7 d/week), versus DFO (at the same dose used for DFO monotherapy) in combination with deferiprone (DFP) (at a dose of 75 mg/kg/day) [DFO+DFP] in patients received prior monotherapy with DFO but had poor response. Endpoints were defined as reducing iron stores in iron overloaded patients and improving cardiac function assessed by left ventricular ejection measurements using Doppler Echocardiogram. Statistical analysis of data sets was performed using Prism Graphpad, version 5.

A total of 493 records of all patients registered at the National Thalassemia Centre in Homs were evaluated. 280 (56.8%) of these patients were diagnosed with BTM, and 245/280 (87.5%) were receiving iron chelation therapy. The average age was 11.35 ± 5.69 year-old (mean ± SD), age range [3-32 year], and male-to-female sex ratiowas 102:103. 39% of the patients were administered DFO, 30% and 10% received oral deferasirox (DFX) and deferiprone (DFP) respectively, whereas 21% received a combination of [DFO + DFP]. The average ferritin concentration of the study population was 3954.89 ± 1431.37 [range from 1362 to 8656] ug/l in 2009, and 4038.22 ± 1572.49 [range from 1173 to 8210] ug/l in 2010. Strikingly, 98% of patients had iron overload; [15% mild, 35% moderate and 48% severe] in 2009, and [12.3% mild, 42.5% moderate and 45.2% severe] in 2010.

Patients on DFX had the lowest ferritin concentrations when compared with these of their peers on the DFO and [DFO + DFP] regimens (P=0.0001 and P=0.02 respectively). Patients of DFX also had the lowest percentage of sever iron overload (31%) in comparison with 58%, 51%, and 40% in patients on DOF, [DFO+DFP], and DFP respectively.

In the prospective observational phase of our study, several comparative assessments were conducted. The combination of [DFO+DFP] reduced ferritin concentration by 14% from a mean baseline concentration of 4662.4 ±1266.17 to 3697.1 ±1547.9 (μg/l) after the study 15 month follow up period (P=0.0006), whereas DFO alone was ineffective. Cardiac function decreased by a percentage of (-4.74 ± 12.89) from 68.64%±6.97% to 60.98%±7.22% in patients on DFO (p= 0.0001) and from 67.39%±6.49% to 63.91%±8.51% in patients receiving combination therapy (p= 0.031). Mean decrease was greater in DFO regimen (-10.53 ± 11.89) than that seen in patients on combination therapy (-4.74 ± 12.89) (p= 0.035).

This study reveals aspects of the current status of ICT outcomes in Syria. Our results prove high prevalence of iron overload in patients with BTM despite their receiving ICTs free of charge. Patients are not achieving target serum ferritin thresholds despite chronic treatment with DFO for iron overload. This may suggest its poor clinical effectiveness within the real-world, and necessitates active measures to improve patients’ compliance. The underlying causes of these suboptimal therapeutic outcomes of all ICT regimens should be further investigated, and the cost-effectiveness of ICTs should be reconsidered by decision makers.

No relevant conflicts of interest to declare.