Impact of medication adherence on the effectiveness of deferasirox for the treatment of transfusional iron overload in myelodysplastic syndrome

Abstract

What is known and objective: Regular blood transfusions in the management of myelodysplastic syndrome (MDS) often lead to iron overload. The main objective of this study was to evaluate the impact of medication adherence on the effectiveness of deferasirox for the treatment of transfusional iron overload in patients with MDS. Secondary objectives were to describe treatment effectiveness and safety in daily clinical practice.

Methods: A longitudinal, retrospective, observational study was carried out in a university hospital. The inclusion criteria were age over 18 years, MDS diagnosis and treatment with deferasirox for transfusion-dependent iron overload during the period of study (from January 2011 to April 2015). Treatment effectiveness was estimated by serum ferritin (SF), and adherence was measured by medication possession ratio (MPR). Clinically relevant analytical alterations during the treatment and reasons for treatment discontinuation were also assessed.

Results: Thirty-five patients were included in the study. Median SF at baseline was 1636 μg/L, and it decreased to 1399 μg/L during follow-up. The median adherence rate was 92%, although only 54·8% of the patients maintained deferasirox adherence ≥90% during the whole duration of treatment. Adherence rate was inversely correlated to SF (r = -0·288, P = 0·004). The median (p25, p75) duration of treatment was 11 (3·0, 37·8) months. The most common reasons for treatment discontinuation were renal toxicity (35%) and patient's death (25%).

What is new and conclusion: Deferasirox's effectiveness, measured by the decrease in SF, was significantly better in adherent patients. The most frequent reason for treatment discontinuation was renal toxicity. Developing strategies to improve deferasirox treatment adherence and monitoring renal function in those patients should be key points in pharmaceutical care.

Keywords: adherence; deferasirox; effectiveness; iron overload; myelodyspastic syndrome; outpatient; safety.