The impact of diagnostic criteria and treatments on the 20-year costs for treating relapsing-remitting multiple sclerosis

Objective: To assess whether the introduction of the new diagnostic criteria and disease modifying therapies (DMTs) is associated with higher cost for treating multiple sclerosis (MS). Methods: This is a regression-based quasi-experimental study employing interrupted time series analysis, including data from 2229 patients (age 42.1 ± 11.2 years; female 63.34%), with incident diagnosis of relapsing remitting MS (RRMS) and followed up from 1997 to 2017, extracted from the database of the MS Clinical Care and Research Centre of the Federico II University Hospital of Naples (Italy). Annual healthcare costs for DMT (e.g., prescription, staff involved in DMT administration) and management (e.g., neurological consultations, other consultations related to DMT safety, MRI, laboratory exams), were calculated and inflated to the most recent value. Results: Annual costs per patient for DMT prescription and management were not affected by the introduction of 2001 and 2005 criteria, but decreased by 0.4% after the introduction of 2011 criteria (PD= -0.4%; 95% C.I. -0.7%/-0.0%; p=0.023). Annual costs per patient increased by 11.2% after the introduction of Natalizumab in 2007 (PD= 11.2%; 95% C.I.= 9.4%/13.0%; p <0.001), by 10.9% after the introduction of tablets in 2011 (Fingolimod, Teriflunomide and Dimethyl Fumarate) (PD= 10.9%; 95% C.I. 9.2%/12.7%; p<0.001), and by 10.7% after the introduction of Alemtuzumab in 2015 (PD= 10.7%; 95% C.I. 9.0%/12.4%; p< 0.001). Discussion: DMTs remain the main responsible for increased medical direct costs in MS, whilst improved diagnostic skills and subsequent patient profiling can at least in part mitigate costs for MS treatment and management.