Adherence to recommended dosing and monitoring for mitoxantrone in patients with multiple sclerosis: a healthcare claims database study supplemented with medical records—the RETRO study†

Purpose Mitoxantrone was approved for treatment of multiple sclerosis (MS) in October 2000. Monitoring and dosing guidelines in the product labeling accompanying this indication include blood counts, liver function, and pregnancy tests at each administration. Due to potential cardiotoxicity, left ventricular ejection fraction (LVEF) testing prior to initial infusion and all infusions at a cumulative dose ≥100 mg/m2 was recommended until April 2005 when LVEF testing before all infusions was recommended in the approved labeling. We sought to estimate provider adherence to dosing and monitoring guidelines and the effect of changes in LVEF monitoring guidelines. Methods MS patients who received mitoxantrone between October 2000 and June 2006 were selected from the claims of a large US health insurer. Claims for infusions and for specified tests prior to an infusion determined adherence to guidelines, with medical records providing additional information for a subset. Results There were 1827 mitoxantrone infusions to 548 eligible patients; medical records were obtained for 261 patients (1096 infusions). Most mitoxantrone recipients were 30–59 years of age and 73% were female. Adherence to recommended dosing was higher than for recommended monitoring. Blood counts were conducted for most infusions (78–83%), while liver function tests (LFT) were performed less often (47–54% of infusions). Pregnancy tests were performed for 10% or fewer of the infusions administered to reproductive age women. Adherence with LVEF testing guidelines improved following labeling changes. Conclusions Adherence to recommended monitoring was incomplete, but amenable to change. Automated assessment through insurance claims supplemented with medical record data provides a balanced means for studying adherence to recommendations. Copyright © 2010 John Wiley & Sons, Ltd.