Assessing Compliance to Iron Chelation Therapy in Patients with Thalassemia.

Introduction: Compliance with Desferrioxamine is the most important factor determining morbidity and mortality in transfusion dependent thalassemia patients. Clinical and laboratory methods to assess compliance are essential in modifying patient treatment and determining efficacy of therapy. Simple screening tools for patient compliance assessment needs to be developed and must be correlated with reliable measurement of iron stores.

Objective: The purpose of this study is to assess a simple compliance tool and compare it with quantitative iron stores.

Methods and Patients: A Likert Numerical Scale assessed Adherence to a chelation program. This scale rated adherence to compliance from 1 (poor) to 5 (excellent). 90 transfusion dependent thalassemia patients underwent a brief interview, followed by the administration of the Likert Numerical scale to both the patient and their corresponding physician. This was followed by quantitation of their Serum Ferritin (SF) and liver iron concentration (LIC) utilizing the LTc- SQUID biosusceptometer (Ferritometer ®, Model 5700, Tristan Technologies, San Diego, USA). A subset of patients was followed serially to determine if compliance and liver iron changed as a result of the initial testing.

Results: LIC was assessed in a total of 90 transfusion-dependent patients with a mean age of 17 years (4 – 48 y). The average duration of transfusion and chelation therapy was 14.6 y (range: 1 – 42) and 12.1 y (1 – 40 yrs), respectively. The median value for LIC was 2307 μg/g-liver (range: 364 – 7570). 78 % of patients rated themselves as very compliant (4 or 5) yet 40% of these patients had elevated LIC > 2500μg/g-liver. 92% of the patients received an identical rating from their physician (Spearman rank R_S = 0.9). 19/28 patients with high compliance ratings had elevated LIC (> 2500 μg/g) secondary to recent onset of chelation therapy or inadequate Desferrioxamine dosing when compared to their PRBC cc/kg/y requirements. In 9 compliant patients, no apparent explanation for their elevated liver iron could be found. A subgroup of 16 patients with a mean age of 17 years (3 – 44y) underwent serial LIC and SF measurements. The median interval between first and last measurements was 10 month (range: 4–15). At the time of first SQUID measurement, the median values for LIC and SF were1202 μg/g-liv (893–6167) and 1502 μg/l (660–4496) respectively. Following counseling concerning the liver iron results, DFO dose changes occurred and compliance rose from 1 (poorest) to 5 (excellent) in 7/8 patients studied. The LIC decreased by 25% (7–60%) as the compliance rate improved. In contrast, the SF fluctuated, but at the time of study testing, 10 patients had a significant increase in serum ferritin despite a lower LIC.

Conclusion: Patient compliance can be adequately assessed and result in improved iron balance. However, SF may underestimate compliance and result in inadequate management. We recommend all patients undergo serial assessment of compliance accompanied with LIC and necessary counseling containing their iron stores.