Effect of drug use calendar on adherence to iron chelation therapy in young thalassemia patients

BACKGROUND: Regular blood transfusions in thalassemia patients can lead to severe complications and iron chelation therapy is required as a treatment. Thalassemia is common in Thailand and the drugs used in iron chelation therapy are deferoxamine and deferiprone. Adherence to the therapy is a key factor for treatment success. OBJECTIVE: To assess the impact of a drug use calendar on deferiprone and deferoxamine adherence in young thalassemia patients. METHODS: A total of 86 young thalassemia outpatients at a Thai tertiary care hospital were recruited into the study. Patients were stratified into two groups based on self-assessment of adherence using a visual analogue scale. One group (n=41) was given a calendar with the schedule of drug use in addition to counselling as standard pharmaceutical care. The second group (n=45) only received the counselling. Adherence to iron chelation therapy was assessed by deferiprone pill or deferoxamine vial counts on six visits (V1 to V6) and results were compared between visits and groups using a multilevel linear regression model. Change in serum ferritin levels after 6 visits (n = 81) were compared using a linear regression model. RESULTS: Adherence significantly increased in both the calendar and non-calendar groups for deferiprone mono- and combination-therapy and for deferoxamine monotherapy. In the calendar groups, average adherence increased by between 2.05 and 5.66% per visit compared to increases of 0.31 to3.92% per visit in the non-calendar groups. A significant difference in the increase in adherence per visit between the calendar and non-calendar groups was only observed for deferiprone monotherapy (3.03% SEM = 0.49vs 1.42% SEM =0.49, respectively, P-value = 0.0078). The serum ferritin level decreased in the calendar group by 20.25ng/mL (SEM = 23.80) and increased in the non-calendar group by 59.63 ng/mL (SEM = 23.01, P-value = 0.0147). CONCLUSION: Provision of a drug use calendar improved adherence to deferoxamine and deferiprone and decreased serum ferritin levels in young Thai thalassemia patients over the improvements obtained from standard counselling.