Long-term treatment risks in multiple sclerosis: risk knowledge and risk perception in a large cohort of mitoxantrone-treated patients

Background: Balancing treatment benefits and risks is part of a shared decision-making process before initiating any treatment in multiple sclerosis (MS). Patients understand, appreciate and profit from evidence-based patient information (EBPI). While these processes are well known, long-term risk awareness and risk processing of patients has not been studied. Mitoxantrone treatment in MS is associated with long-term major potential harms – leukaemia (LK) and cardiotoxicity (CT). The risk knowledge and perception among patients currently or previously treated with mitoxantrone is unknown. Objectives: The objective of this article is to conduct a retrospective cohort study in greater Hamburg, Germany, to estimate risk awareness and perception in MS patients treated with mitoxantrone. Methods: MS patients with at least one dose of mitoxantrone between 1991 and 2010 from six major MS centres in greater Hamburg received a questionnaire assessing risk awareness and perception as well as a written EBPI about mitoxantrone-associated LK and CT. Results: Fifty-one per cent in the cohort of n = 575 patients returned the questionnaire. Forty per cent correctly estimated the risk of LK (CT 16%); 56% underestimated the risk (CT 82%). Reading the information increased the accuracy of LK risk estimation, and patients did not report an increase of worries. The EBPI was appreciated and recommended by 85%. Conclusion: Risk awareness of mitoxantrone-treated patients is insufficient, but can be increased by EBPI without increasing worries. Continued patient information during and after treatment should be implemented in management algorithms.